Riverbank Publications No. 50 : The Production and Detection of Messages in Concealed Writing and Images
Geneva, Illinois: Riverbank Laboratories 1918. First Edition. 20 pages 8 3/4 x 11 1/4 inches. (22.3 cm x 28.5 cm). Publisher's stiff tan wrappers with black printed front cover duplicating title page. Provided in the originally issued Riverbank Laboratories button and string flapped manila envelope with limitation number on outside..... More
