Ten cent pocket series appears on t.p., published Apr. 1922-Sept. 1923; Little blue book appears on cover, published late Nov. 1923 and later. Copies printed for a previous series sometimes had new wrappers attached when the series name changed. Cf. Johnson & Tanselle. Haldeman-Julius. (PBSA 64 (1970): 29-78), 37, 48., Series no. printed in type larger than the series name; type 2b, light blue wrappers, no imprint on front. The series no. was printed in type no larger than the series name until early 1924. Cf. Johnson & Tanselle. Haldeman-Julius. (PBSA 64 (1970): 29-78), 49-50., 'Other titles in pocket series': p. 54-59., and Pages [60-64] are blank.