Publisher: The Citadel Press
Years: 1961-1973
Related Series: --
The series numbering is confusing for this one, starting at first glance with C-62, Shaw's The Crime of Imprisonment. What I think actually happened is that the titles from C-62 through C-99 were probably Citadel back catalog titles that were either given their series numbers retroactively after the series began in earnest with C-100 or that were published in one go at the initiation of the Citadel Paperbacks line in 1961. The primary reason for this conclusion is that titles from C-63 to C-99 are in (albeit slightly incorrect*) alphabetical order. Shaw's Crime of Imprisonment is first, at C-62, for some reason. Maybe it was mistakenly left out of the alphabetical order or added later. Titles from C-100 on are all from 1961 or later and aren't arranged alphabetically, reflecting a more typical order of publication.
* Incorrect only because C-82 & C-83 (The Philosophy of Benedetto Croce and The Philosophers of China) and C-95 & C-96 (Therapy Through Hypnosis and Theories in Logic) are mistakenly out of alphabetical order.
A 1963 advertisement for the series (Quality Paperbacks from Citadel Press, NY TIMES BOOK REVIEW, Apr. 7, 1963, at 30, https://timesmachine.nytimes.com/timesmachine/1963/04/07/issue.html (image #263)) lists titles from C-62 to C-130. This listing leads me to believe that titles from C-62 to C-99 were probably retroactively given these series numbers, possibly only for the purpose of ordering them from the ad, as those titles are largely in alphabetical order. The only exceptions are the first title, C-62 (G.B. Shaw's The Crime of Imprisonment) and two others that are probably errors in alphabetization (C-82-83, The Philosophy of Benedetto Croce and The Philosophers of China & C-95-96, Therapy Through Hypnosis and Theories in Logic)).