Theatre Design & Technology - Winter 1981 - 20

Figure 5

Stereo

M-S

'-'~
__","""",.L.41'./.L/'J

*i~
."

*

I

.-~j,;~

...........

'-'"~~

_~

PZM Microphone
facing straight towards the center of the ensemble (the Middle
mic) and a bidirectional or figure-eight microphone oriented left
and right (the Side mic)(see Fig. 5). Because of the orientation
of the two elements, the cardioid element picks up the center
area, algebraically represented by L + R, any sound common to
both left and right. The figure eight element reproduces the
difference signal, L - R, or anything not in the center of the
stereo image. The two microphone signals, when added together, first in polarity and then out of polarity, yield an accurate left
and right stereo image that is pleasant to listen to in stereo and
gives excellent mono compatibility. Of course, to achieve the
best monophonic blending the two microphones should be as
close to each other as possible. There are stereo microphones
that combine two separate elements in the same case, each one
with an adjustable pickup pattern, separated by fractions of an
inch, that assure accurate mono blending of the signals. The
adjustable patterns allow the same stereo microphone to be
used for X - Y, M - S, or other stereo pickup techniques not
mentioned here.

The Pressure Zone Microphone
No contemporary article on microphones would be complete
without mentioning the pressure zone microphone or PZM™
The pressure zone microphone is an omnidirectional microphone specifically designed to take advantage of the f100rwave
and direct sound wave coincidently. Its diaphragm is small,

about '14" in diameter, making its impulse or transient response
very good. The PZM is not a contact microphone as some
people say, but rather, a pressure transducer that takes advantage of the pressure zone that develops as a vibrating air
molecule bounces off a reflecting surface. The microphone
works best on a large boundary surface such as a wall or floor
but I have also used them attached to plexiglas sheets about 3'
x 4' flown over an ensemble with some success.
The PZM is well suited for dramatic work. I have used them for
sound reinforcement, built them into sets (or coffins in the case
of a recent production of Dracula), and even used them as
lavaliere microphones on performers. Although the PZM is an
omnidirectional microphone, its directional characteristics can
be controlled by using some sound absoprtion material next to
the "dead" side of the microphone.
While it may be argued that the frequency response of many
microphones is flatter than that of the PZM by 2 or 3 dB, and the
PZM really is not that efficient a transducer, a PZM makes you
think more about microphone placement with an eye (or ear)
toward phasing problems than a standard microphone does.
A $500 studio microphone placed within a few inches of a
reflecting surface can create notches and dips in the frequency
response that might be 20-30 dB deep. A PZM, however, will not
exhibit these comb filtering effects when properly positioned,
making the 2 or 3 dB variation in its response the limiting factor
in recording instead of the 20 or 30 dB dips caused by incorrect
placement of the studio microphone.
A final word about PZM's. Although a floor mounting is an
excellent location there are situations where it just will not work.
Trying to record an orchestra, for example, with the microphones-PZM or otherwise-at the edge of the stage a few feet
from the orchestra, will probably result in poor balance between
sections. The violins will be almost on top of the microphones
while the brass and woodwinds might be three or four times
farther away. Recall what varying the distance between microphone and performer does to the reverberation quality of the
recording. The violins will wind up sounding too dry while the
brass/woodwinds will probably be too reverberant. The solution
is to fly the microphones so that the ratio of differences in
subject-to-microphone distances will be less. The PZM in a floor
mount configuration is hard to beat for small ensembles, piano
(try taping one to the inside of the cover for a tight sound), or
vocalists, but for the larger groups, conventional placements still
have an edge.
This article is by no means exhaustive, and the serious
practitioner is encouraged to peruse some of the excellent
books and articles written on the subject, some of which are
included in the bibliography. Everyone should experiment with
their microphones. They are tools, not magic, and will give you
good performance even if they are not "megabuck" studio
models, if they are placed with some thought to their acoustic
environment and their relationship to the placement of other
microphones in the setup.D

References/Suggested Reading
Barclay, Clay. "PZM, Theory and Practice of a New Microphone
Design." DB-The Sound Engineering Magazine, June 1981.
Bartlett, Bruce. "Stereo Microphone Techniques." DB- The Sound Engineering Magazine, December 1979.
Burroughs, Lou. Microphones: Design and Application. New York:
Sagamore Publishing Co. Inc., 1974.
Collison, David. Stage Sound. New York: Drama Book Specialists
(Publishers). 1976.
Davis, Don and Carolyn. Sound System Engineering. Indianapolis:
Howard W. Sams and Co. Inc., 1975.
Eargle, John. Sound Recording. New York: Van Nostrand Reinhold Co.,
1976.
Olson, Harry F. Modern Sound Reproduction. New York: Van Nostrand
Reinhold Co., 1972.

Tom Hayes holds degrees in physics, technical theater, and broadcasting. He is currently Audio Director at Krannert Center for the Performing Arts.
18

Theatre Design & Technology

USITIlWinter, 1981



Table of Contents for the Digital Edition of Theatre Design & Technology - Winter 1981

Contents
Theatre Design & Technology - Winter 1981 - 1
Theatre Design & Technology - Winter 1981 - 2
Theatre Design & Technology - Winter 1981 - 3
Theatre Design & Technology - Winter 1981 - Contents
Theatre Design & Technology - Winter 1981 - 5
Theatre Design & Technology - Winter 1981 - 6
Theatre Design & Technology - Winter 1981 - 7
Theatre Design & Technology - Winter 1981 - 8
Theatre Design & Technology - Winter 1981 - 9
Theatre Design & Technology - Winter 1981 - 10
Theatre Design & Technology - Winter 1981 - 11
Theatre Design & Technology - Winter 1981 - 12
Theatre Design & Technology - Winter 1981 - 13
Theatre Design & Technology - Winter 1981 - 14
Theatre Design & Technology - Winter 1981 - 15
Theatre Design & Technology - Winter 1981 - 16
Theatre Design & Technology - Winter 1981 - 17
Theatre Design & Technology - Winter 1981 - 18
Theatre Design & Technology - Winter 1981 - 19
Theatre Design & Technology - Winter 1981 - 20
Theatre Design & Technology - Winter 1981 - 21
Theatre Design & Technology - Winter 1981 - 22
Theatre Design & Technology - Winter 1981 - 23
Theatre Design & Technology - Winter 1981 - 24
Theatre Design & Technology - Winter 1981 - 25
Theatre Design & Technology - Winter 1981 - 26
Theatre Design & Technology - Winter 1981 - 27
Theatre Design & Technology - Winter 1981 - 28
Theatre Design & Technology - Winter 1981 - 29
Theatre Design & Technology - Winter 1981 - 30
Theatre Design & Technology - Winter 1981 - 31
Theatre Design & Technology - Winter 1981 - 32
Theatre Design & Technology - Winter 1981 - 33
Theatre Design & Technology - Winter 1981 - 34
Theatre Design & Technology - Winter 1981 - 35
Theatre Design & Technology - Winter 1981 - 36
Theatre Design & Technology - Winter 1981 - 37
Theatre Design & Technology - Winter 1981 - 38
Theatre Design & Technology - Winter 1981 - 39
Theatre Design & Technology - Winter 1981 - 40
Theatre Design & Technology - Winter 1981 - 41
Theatre Design & Technology - Winter 1981 - 42
Theatre Design & Technology - Winter 1981 - 43
Theatre Design & Technology - Winter 1981 - 44
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2020winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2020winter_public
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2019fall_public
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2019fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2019summer_public
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2019summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2019spring_public
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2019spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/usitt_techexpoguide_2019_public
http://www.nxtbook.com/nxtbooks/hickmanbrady/usitt_techexpoguide_2019
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2019winter_public
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2019winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2018fall_public
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2018fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2018summer_public
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2018summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2018spring_public
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2018spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2018winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2017fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2017fall_public
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2017summer_public
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2017summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2017spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2017spring_public
http://www.nxtbook.com/nxtbooks/hickmanbrady/usitt_techexpoguide_2017_public
http://www.nxtbook.com/nxtbooks/hickmanbrady/usitt_techexpoguide_2017
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2017winter_public
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2017winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2016fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2016summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2016spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2016spring_public
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2016winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2015fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2015summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2015spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2015winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2014fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2014summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2013winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2013summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2013fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2013spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2012winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2012fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2012summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2012spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2011winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2011fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2011summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2011spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2010winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2010fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2010summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2010spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2009winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2009fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2009summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2009spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2008winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2008fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2008summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2008spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2007winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2007fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2007summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2007spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2006winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2006fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2006summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2006spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2005winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2005fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2005summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2005spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2004winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2004fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2004summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2004spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2003winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2003fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2003summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2003spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2002winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2002fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2002summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2002spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2001winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2001fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2001summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2001spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2000winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2000fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2000summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2000spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1999winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1999fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1999summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1999spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1998winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1998fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1998summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1998spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1997winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1997fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1997summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1997spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1996winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1996fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1996summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1996spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1995winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1995fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1995summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1995spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1994winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1994fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1994summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1994spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1993winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1993fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1993summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1993spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1992winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1992fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1992summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1992spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1991winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1991fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1991summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1991spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1990fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1990summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1990spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1989winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1989fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1989summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1989spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1988winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1988winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1988fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1988summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1988spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1987winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1987fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1987summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1987spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1986winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1986fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1986summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1986spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1985winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1985fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1985summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1985spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1984fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1984summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1984spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1983winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1983fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1983summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1983spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1982winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1982fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1982summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1982spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1981winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1981fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1981summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1981spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1980winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1980fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1980summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1980spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1979winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1979fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1979summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1979spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1978winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1978fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1978summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1978spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1977winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1977fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1977summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1977spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1976winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1976fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1976summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1976spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1975winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1975fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1975summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1975spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1974Dec
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1974Oct
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1974May
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1974Feb
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1973Dec
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1973Oct
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1973May
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1973Feb
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1972Dec
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1972Oct
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1972May
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1972Feb
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1971Dec
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1971Oct
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1971May
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1971Feb
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1970Dec
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1970Oct
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1970May
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1970Feb
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1969Dec
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1969Oct
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1969May
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1969Feb
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1968Dec
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1968Oct
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1968May
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1968Feb
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1967Dec
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1967Oct
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1967May
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1967Feb
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1966Dec
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1966Oct
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1966May
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1966Feb
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1965Dec
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1965Oct
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1965May
http://www.nxtbookMEDIA.com