serialised in galaxy vol.10 #3, #4, #5, #6; 6, 7, 8, 9/1955 (bre #30, #31, #32, #33)
part one cover story, art by fred kirberger (signed kirberger),
all four parts 4 b+w illustrations each, by sanford kossin (bre have respectively 4, 3, 2, & 4 only of these).
collaborative pseudonym of lester del rey and frederik pohl
written° by them at the request of h. l. gold, editor of galaxy to be the prize-winning novel in a competition for the best sf novel by a previously-unpublished author, none of the received competition entries being judged publishable by h. l. gold or the editors at the co-sponsoring h/cvr publishers, simon & schuster.
° - or agreed to be entered under the pseudonym as a first novel and winner of the competition, at his request; accounts have differed slightly, over the decades.
first edition published in hardcover by simon & schuster 1955 q.v.