I'm not sure if a list of cipher, cryptogram, and secret writing books published prior to 1970 have been listed yet.
I heard this tid-bit about ciphers on the National Geographic documentary "Code Breakers" featuring the zodiac 340 cipher. A computer scientist by the name of Ryan Garlick from the University of North Texas said, “he (zodiac) may have used some books that were available at the time. So, if chapter 1 of that book is homophonic substitution ciphers, and we know that that’s how the first solved cipher was encoded, then we definitely want to look at chapter 2 in that book to see how this one (the 340 cipher) might be decoded."
Here's a list of books I could find published prior to 1970, yet still within range for someone to own the book or check it out from the public library:
a) Codes and Secret Writing by Herbert Spencer Zim 1966
b) Codes and Ciphers: Secret Writings through the Ages by John Laffin 1967
c) The Code Breakers: The story of secret writing by David Kahn 1967
d) Cryptography: The Science of Secret Writing by Laurence D. Smith 1955
e) Secret Writing: An introduction to ciphers, cryptograms, and codes by Henry Lysing 1936
f) Secret Writing: An introduction to ciphers, cryptograms, and codes by John L Nonovic 1936
g) Cloak and Cipher: A History of Secret Writing by Dan Tyler and Martha Moore 1962
h) Secret and Urgent: The Story of Codes and Ciphers by Fletcher Pratt 1942
i) The First Book of Codes and Ciphers by Sam Epstein and Beryl Williams Epstein 1956
j) Secret Codes and Ciphers by Bernice Kohn Hunt 1968
k) Fun with Cryptograms by Joseph Verner Reed 1968
l) Secret Code Book by Francis W. Keene 1955
m) An Invitation to Cryptograms by Eugenia Williams 1959
n) Cryptanalysis: A Study of Ciphers and their solution by Helen Fouchel Gaines 1956
o) Secrets with Ciphers and Codes by Joel Rothman and Ruthven Tremain 1969
p) How to Write Codes and Send Secret Messages by John Lawrence Peterson 1966
q) A Guide to Codes and Signals by Gordon A J Petersen 1942
r) Elementary Cryptanalysis by Abraham Sinkov in 1968
s) Codes and Ciphers by Alexander d’Agapeyeff 1952


