Cambridge: At the University Press 1957. Later printing. xvi, , 302,  pages. Publisher's grey cloth with red and black printed dust jacket. The second printing, issued in the same year as the first, 1957. Dust jacket noting "Second impression" and with five dollar retail price. Dj with lower corner clipped, some scuffing to the rear panel and with minor wear at the extremities. Binding with touch of shelf wear on the bottom edge. SIGNED in 1974 by AUTHOR Elizebeth S. Friedman. Near Fine / Near Fine. Cloth. 
The Friedman's were famous cryptologists during World War I and were instrumental in breaking codes during that war. Many secret works by William Friedman's were published through the Riverbank Laboratories where he and Elizebeth met. After retirement, they continued with a lifelong hobby, examining Shakespearean Ciphers, and objectively evaluating their efficacy. This book is the result. Scarce signed by either author. William F. Friedman died in 1969. Elizebeth S. Friedman died in 1980.