Theatre Design & Technology - Summer 2017 - Public - 40

Figure 4 - Custom cabinet and venting solutions can be fabricated after
consultation with appropriate experts.

per hour, sometimes called the air change rate, which
is the measure of how often the air in a room is replaced.
The phrase "10 air changes per hour" is a common recommendation in darkroom photography ventilation, which
can be similar to air change rates for theatres and classrooms. The big distinction for darkroom photography is
that the air vented out is sent outside the building and not
recirculated. Recirculating air typically adds 5 to 30 percent
of fresh outside air, while the same amount of inside air
is exhausted out, so the majority of the air is just reused.
This recirculation is common in comfort HVAC systems
because they are primarily looking at controlling the CO2
levels. For workspaces that introduce chemicals, replacing
exhausted air is recommended.
One option for dealing with air contaminant exposure
is to leave the room while the printer is in use, although
this is unlikely to be a viable solution for most users. If a
printer is specified for unsupervised operation, then it may
be possible to print unattended and only enter the room
hours after the print is finished; however, most low-cost
consumer models are not designed for this type of operation. In practice, clearing the work area is a very impractical
solution due to its inefficient use of resources.
Two more practical and common methods of mitigating particulates in the air include diluting the amount
of particulates in the area and exhausting the fumes out
of the workspace entirely. OSHA explains the options like
this: "General exhaust ventilation, also called dilution ventilation, is different from local exhaust ventilation because
instead of capturing emissions at their source and removing them from the air, general exhaust ventilation allows
the contaminant to be emitted into the workplace air and
then dilutes the concentration of the contaminant to an
acceptable level (e.g., to the PEL or below). Dilution systems are often used to control evaporated liquids." General
exhaust ventilation is usually considered appropriate when
the hazards are diluted in the air and are a 'relatively low
40

theatre design

& technology

S u m m e r   2 0 1 7

hazard' like most airborne dusts. Whereas a local exhaust is
required for larger particles (like sawdust) or more hazardous particles emitted from a single point like spray booth
or 3D printer. A detailed explanation can be found on OSHA's website (https://tinyurl.com/osha3D). While having
general exhaust can help with air quality, it is not effective for fumes with very low PELs or TLVs. (Remember,
the lower the value the higher the toxicity.) To understand
what may be required to reduce the airborne chemicals
from 3D printers and to address operator exposure, it is
helpful to look at the SDSs for the materials again. The
sometimes innocuous phrasing used by manufacturers can
have some deeper implications.
SDS Sheets: While the information on Safety Data
Sheets for 3D printers is incredibly varied and sometimes
conflicting, most do specify local ventilation. Users will see
general advisories about the need for ventilation because
of the fumes produced through 3D printing. For instance,
Makerbot's SDS for their brands of ABS and PLA plastic
specifies: "Provide local exhaust ventilation system. Ventilation should be sufficient to effectively remove and prevent buildup of any dusts or fumes that may be generated
during handling or thermal processing" (Makerbot ABS
SDS).
However, the focus on ventilation can obscure other
risks, particularly for casual users and readers. For example,
Ultimaker specifies for their brand of ABS: "Good general
ventilation (typically 10 air changes per hour) is recommended." They also recommend "process enclosures, local exhaust ventilation, or other engineering controls that
maintain airborne levels below recommended exposure
limits." But there are no PELs or TLVs mentioned on
their data sheet to guide users with assessing those exposure limits. In fact, in the hazards identification section it
notes: "No risk exists to the health of users if the product
is handled and processed properly" (Ultimaker ABS SDS).
The latter could be seen as downplaying the potential risks,
given that we are unsure about the PELs and TLVs.
As discussed earlier, the lack of discussion of PELs
does not mean that no hazardous fumes are emitted during printing. Consider the Safety Data Sheet for Formlabs resin, which suggests: "Ventilation Controls: Ensure
adequate ventilation." The same Formlabs SDS states that
there are no OSHA PELs for the components in the resin.
All that means is that the components listed are not among
the tiny percentage of chemicals that have been tested by
OSHA. But if we look at other chemicals common in resins, they all have a very low value. Butadiene, one of the byproducts of ABS plastic, has a PEL of one part per million.
Some resins, like the ones by FormLabs, use methacrylic
acid esters mixed with other chemicals. Methacrylic acid
has a PEL of 20 parts per million. In comparison, carbon
dioxide has a PEL of 5,000 parts per million. That should


https://www.tinyurl.com/osha3D

Table of Contents for the Digital Edition of Theatre Design & Technology - Summer 2017 - Public

Contents
Theatre Design & Technology - Summer 2017 - Public - Cover1
Theatre Design & Technology - Summer 2017 - Public - Cover2
Theatre Design & Technology - Summer 2017 - Public - 1
Theatre Design & Technology - Summer 2017 - Public - 2
Theatre Design & Technology - Summer 2017 - Public - Contents
Theatre Design & Technology - Summer 2017 - Public - 4
Theatre Design & Technology - Summer 2017 - Public - 5
Theatre Design & Technology - Summer 2017 - Public - 6
Theatre Design & Technology - Summer 2017 - Public - 7
Theatre Design & Technology - Summer 2017 - Public - 8
Theatre Design & Technology - Summer 2017 - Public - 9
Theatre Design & Technology - Summer 2017 - Public - 10
Theatre Design & Technology - Summer 2017 - Public - 11
Theatre Design & Technology - Summer 2017 - Public - 12
Theatre Design & Technology - Summer 2017 - Public - 13
Theatre Design & Technology - Summer 2017 - Public - 14
Theatre Design & Technology - Summer 2017 - Public - 15
Theatre Design & Technology - Summer 2017 - Public - 16
Theatre Design & Technology - Summer 2017 - Public - 17
Theatre Design & Technology - Summer 2017 - Public - 18
Theatre Design & Technology - Summer 2017 - Public - 19
Theatre Design & Technology - Summer 2017 - Public - 20
Theatre Design & Technology - Summer 2017 - Public - 21
Theatre Design & Technology - Summer 2017 - Public - 22
Theatre Design & Technology - Summer 2017 - Public - 23
Theatre Design & Technology - Summer 2017 - Public - 24
Theatre Design & Technology - Summer 2017 - Public - 25
Theatre Design & Technology - Summer 2017 - Public - 26
Theatre Design & Technology - Summer 2017 - Public - 27
Theatre Design & Technology - Summer 2017 - Public - 28
Theatre Design & Technology - Summer 2017 - Public - 29
Theatre Design & Technology - Summer 2017 - Public - 30
Theatre Design & Technology - Summer 2017 - Public - 31
Theatre Design & Technology - Summer 2017 - Public - 32
Theatre Design & Technology - Summer 2017 - Public - 33
Theatre Design & Technology - Summer 2017 - Public - 34
Theatre Design & Technology - Summer 2017 - Public - 35
Theatre Design & Technology - Summer 2017 - Public - 36
Theatre Design & Technology - Summer 2017 - Public - 37
Theatre Design & Technology - Summer 2017 - Public - 38
Theatre Design & Technology - Summer 2017 - Public - 39
Theatre Design & Technology - Summer 2017 - Public - 40
Theatre Design & Technology - Summer 2017 - Public - 41
Theatre Design & Technology - Summer 2017 - Public - 42
Theatre Design & Technology - Summer 2017 - Public - 43
Theatre Design & Technology - Summer 2017 - Public - 44
Theatre Design & Technology - Summer 2017 - Public - 45
Theatre Design & Technology - Summer 2017 - Public - 46
Theatre Design & Technology - Summer 2017 - Public - 47
Theatre Design & Technology - Summer 2017 - Public - 48
Theatre Design & Technology - Summer 2017 - Public - 49
Theatre Design & Technology - Summer 2017 - Public - 50
Theatre Design & Technology - Summer 2017 - Public - 51
Theatre Design & Technology - Summer 2017 - Public - 52
Theatre Design & Technology - Summer 2017 - Public - 53
Theatre Design & Technology - Summer 2017 - Public - 54
Theatre Design & Technology - Summer 2017 - Public - 55
Theatre Design & Technology - Summer 2017 - Public - 56
Theatre Design & Technology - Summer 2017 - Public - 57
Theatre Design & Technology - Summer 2017 - Public - 58
Theatre Design & Technology - Summer 2017 - Public - 59
Theatre Design & Technology - Summer 2017 - Public - 60
Theatre Design & Technology - Summer 2017 - Public - 61
Theatre Design & Technology - Summer 2017 - Public - 62
Theatre Design & Technology - Summer 2017 - Public - 63
Theatre Design & Technology - Summer 2017 - Public - 64
Theatre Design & Technology - Summer 2017 - Public - 65
Theatre Design & Technology - Summer 2017 - Public - 66
Theatre Design & Technology - Summer 2017 - Public - 67
Theatre Design & Technology - Summer 2017 - Public - 68
Theatre Design & Technology - Summer 2017 - Public - Cover3
Theatre Design & Technology - Summer 2017 - Public - Cover4
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2021winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2021winter_public
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2020fall_public
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2020fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2020summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2020summer_public
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2020spring_public
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2020spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2020winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2020winter_public
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2019fall_public
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2019fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2019summer_public
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2019summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2019spring_public
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2019spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/usitt_techexpoguide_2019_public
https://www.nxtbook.com/nxtbooks/hickmanbrady/usitt_techexpoguide_2019
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2019winter_public
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2019winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2018fall_public
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2018fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2018summer_public
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2018summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2018spring_public
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2018spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2018winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2017fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2017fall_public
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2017summer_public
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2017summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2017spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2017spring_public
https://www.nxtbook.com/nxtbooks/hickmanbrady/usitt_techexpoguide_2017_public
https://www.nxtbook.com/nxtbooks/hickmanbrady/usitt_techexpoguide_2017
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2017winter_public
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2017winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2016fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2016summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2016spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2016spring_public
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2016winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2015fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2015summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2015spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2015winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2014fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2014summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2013winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2013summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2013fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2013spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2012winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2012fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2012summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2012spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2011winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2011fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2011summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2011spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2010winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2010fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2010summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2010spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2009winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2009fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2009summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2009spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2008winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2008fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2008summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2008spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2007winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2007fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2007summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2007spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2006winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2006fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2006summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2006spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2005winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2005fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2005summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2005spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2004winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2004fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2004summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2004spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2003winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2003fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2003summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2003spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2002winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2002fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2002summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2002spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2001winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2001fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2001summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2001spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2000winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2000fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2000summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2000spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1999winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1999fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1999summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1999spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1998winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1998fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1998summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1998spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1997winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1997fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1997summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1997spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1996winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1996fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1996summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1996spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1995winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1995fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1995summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1995spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1994winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1994fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1994summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1994spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1993winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1993fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1993summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1993spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1992winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1992fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1992summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1992spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1991winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1991fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1991summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1991spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1990fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1990summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1990spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1989winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1989fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1989summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1989spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1988winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1988winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1988fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1988summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1988spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1987winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1987fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1987summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1987spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1986winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1986fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1986summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1986spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1985winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1985fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1985summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1985spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1984fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1984summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1984spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1983winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1983fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1983summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1983spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1982winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1982fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1982summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1982spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1981winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1981fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1981summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1981spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1980winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1980fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1980summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1980spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1979winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1979fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1979summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1979spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1978winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1978fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1978summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1978spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1977winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1977fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1977summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1977spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1976winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1976fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1976summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1976spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1975winter
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1975fall
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1975summer
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1975spring
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1974Dec
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1974Oct
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1974May
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1974Feb
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1973Dec
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1973Oct
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1973May
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1973Feb
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1972Dec
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1972Oct
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1972May
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1972Feb
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1971Dec
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1971Oct
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1971May
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1971Feb
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1970Dec
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1970Oct
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1970May
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1970Feb
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1969Dec
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1969Oct
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1969May
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1969Feb
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1968Dec
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1968Oct
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1968May
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1968Feb
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1967Dec
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1967Oct
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1967May
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1967Feb
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1966Dec
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1966Oct
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1966May
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1966Feb
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1965Dec
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1965Oct
https://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1965May
https://www.nxtbookmedia.com