Publisher: G.P. Putnam's Sons
Related Series: --
Capricorn Books were originally intended to be published in 1958 but ended up being delayed to March 1959. Starting in 1960 larger books were published as Capricorn Giants starting with CAP GIANT 201. The main sequence had only made it to CAP 172 by 1972, after which all subsequent Capricorn Books were published under the GIANT designation until 1978. The two sequences are separated in two tables below, but there's overlap in publication date from 1960-1972.
Putnam's to Enter the Paperback Field, PW, Aug. 18, 1958, at 30.
Forecast of Paperbacks: Capricorn Books, PW, Jan. 19, 1959, at 115:
CAPRICORN BOOKS Putnam (March 1)
The first six titles in Putnam's new paperback line were discussed in PW's Forecast of Paperbacks, November 17, page 54. Publication was scheduled for mid-January, but has been postponed to the first of March.