Theatre Design & Technology - Winter 2008 - 14

FT F Fg F FT Fg F Ffr F F FN Fg F F FT Ffr FN F
friction (either static or kinetic friction, depending on
whether or not the skid is moving). In the static case, we get
Fnet, x = 0 = FT, 1- FT, 2 - Ffr, s .
We're again taking direction into account. F T, 1 is pulling in
the positive direction and F T, 2 and F fr, s point in the opposite
(negative) direction. The kinetic case is similar-just replace
the "s" for static friction with a "k". Solving this equation, we
get Ffr, s = FT, 1 - FT, 2 for when the skid is stationary and Ffr, k
= FT, 1 - FT, 2 when the skid is moving.
Using these equations, along with the equation for the
magnitude of the frictional forces given above, we can put everything together to find equations for the coefficients of static
and kinetic friction. We find that

Figure 6a. Coefficients of
friction on UHMW.

→

→

→

for both the static and kinetic cases. FT, 1 and FT, 2 were measured using our load cells, and FN was equal to the weight of
the skid (and everything on top of it).

A NOTE ON EXPERIMENTAL UNCERTAINTY
Any time you take data in an experiment, there is some uncertainty associated with each measurement. This isn't because of
any mistakes that you might make (although you do need to
watch out for those) but because of minor variations in materials, the limitations of your equipment, and other random
factors over which you have no control. For example, if you're
making measurements with a ruler, you can't measure any
more accurately than the smallest divisions on your ruler, and
if you're trying to be that precise, any minor variation in where
you place the end of the ruler or how you read it (the angle
of your head, etc.) will affect your measurements. This is why
we don't just make one measurement, but, in this case, one
hundred, so that we can average out these uncertainties. In the
tables at right, we also include an estimate of our uncertainties (determined by taking the standard deviation of each set
of measurements). What this means is that if a coefficient of
friction is reported as 0.25 ± 0.04, it should be treated as
being somewhere in between 0.21 and 0.29, and you should
take that range into consideration in any calculations you
perform.

Figure 6b. Coefficients of
friction on painted MDF.

Figure 6c. Coefficients of
friction on MDF.

Figure 6d. Coefficients of
friction on glazed lauan.

Figure 6e. Coefficients of
friction on painted hardboard.

THE DATA
In the tables at right, the top line indicates the base material
for that group of tests. The first column lists the skid materials
used, the second, the coefficients of static friction (including
experimental uncertainty), and the third, the coefficients of kinetic friction (again including experimental uncertainty).

Figure 6f. Coefficients of
friction on painted and sealed
hardboard.

USING THIS DATA
Before using this data, there are a few things to take into
consideration:

W I N T E R

2008

THEATRE

DESIGN

&

TECHNOLOGY

13



Table of Contents for the Digital Edition of Theatre Design & Technology - Winter 2008

Contents
Theatre Design & Technology - Winter 2008 - 1
Theatre Design & Technology - Winter 2008 - 2
Theatre Design & Technology - Winter 2008 - 3
Theatre Design & Technology - Winter 2008 - Contents
Theatre Design & Technology - Winter 2008 - 5
Theatre Design & Technology - Winter 2008 - 6
Theatre Design & Technology - Winter 2008 - 7
Theatre Design & Technology - Winter 2008 - 8
Theatre Design & Technology - Winter 2008 - 9
Theatre Design & Technology - Winter 2008 - 10
Theatre Design & Technology - Winter 2008 - 11
Theatre Design & Technology - Winter 2008 - 12
Theatre Design & Technology - Winter 2008 - 13
Theatre Design & Technology - Winter 2008 - 14
Theatre Design & Technology - Winter 2008 - 15
Theatre Design & Technology - Winter 2008 - 16
Theatre Design & Technology - Winter 2008 - 17
Theatre Design & Technology - Winter 2008 - 18
Theatre Design & Technology - Winter 2008 - 19
Theatre Design & Technology - Winter 2008 - 20
Theatre Design & Technology - Winter 2008 - 21
Theatre Design & Technology - Winter 2008 - 22
Theatre Design & Technology - Winter 2008 - 23
Theatre Design & Technology - Winter 2008 - 24
Theatre Design & Technology - Winter 2008 - 25
Theatre Design & Technology - Winter 2008 - 26
Theatre Design & Technology - Winter 2008 - 27
Theatre Design & Technology - Winter 2008 - 28
Theatre Design & Technology - Winter 2008 - 29
Theatre Design & Technology - Winter 2008 - 30
Theatre Design & Technology - Winter 2008 - 31
Theatre Design & Technology - Winter 2008 - 32
Theatre Design & Technology - Winter 2008 - 33
Theatre Design & Technology - Winter 2008 - 34
Theatre Design & Technology - Winter 2008 - 35
Theatre Design & Technology - Winter 2008 - 36
Theatre Design & Technology - Winter 2008 - 37
Theatre Design & Technology - Winter 2008 - 38
Theatre Design & Technology - Winter 2008 - 39
Theatre Design & Technology - Winter 2008 - 40
Theatre Design & Technology - Winter 2008 - 41
Theatre Design & Technology - Winter 2008 - 42
Theatre Design & Technology - Winter 2008 - 43
Theatre Design & Technology - Winter 2008 - 44
Theatre Design & Technology - Winter 2008 - 45
Theatre Design & Technology - Winter 2008 - 46
Theatre Design & Technology - Winter 2008 - 47
Theatre Design & Technology - Winter 2008 - 48
Theatre Design & Technology - Winter 2008 - 49
Theatre Design & Technology - Winter 2008 - 50
Theatre Design & Technology - Winter 2008 - 51
Theatre Design & Technology - Winter 2008 - 52
Theatre Design & Technology - Winter 2008 - 53
Theatre Design & Technology - Winter 2008 - 54
Theatre Design & Technology - Winter 2008 - 55
Theatre Design & Technology - Winter 2008 - 56
Theatre Design & Technology - Winter 2008 - 57
Theatre Design & Technology - Winter 2008 - 58
Theatre Design & Technology - Winter 2008 - 59
Theatre Design & Technology - Winter 2008 - 60
Theatre Design & Technology - Winter 2008 - 61
Theatre Design & Technology - Winter 2008 - 62
Theatre Design & Technology - Winter 2008 - 63
Theatre Design & Technology - Winter 2008 - 64
Theatre Design & Technology - Winter 2008 - 65
Theatre Design & Technology - Winter 2008 - 66
Theatre Design & Technology - Winter 2008 - 67
Theatre Design & Technology - Winter 2008 - 68
Theatre Design & Technology - Winter 2008 - 69
Theatre Design & Technology - Winter 2008 - 70
Theatre Design & Technology - Winter 2008 - 71
Theatre Design & Technology - Winter 2008 - 72
Theatre Design & Technology - Winter 2008 - 73
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