C.O.D. Mars / Alien Sea

From Author Wars - https://authorwars.com/books/cod-mars--alien-sea-792281.html

Overview:

Title: C.O.D. Mars / Alien Sea
Author: John Rackham E. C. Tubb
Year: 1968
Type: Omnibuses

Editions/Publications:

Unknown. C.O.D. Mars / Alien Sea (Unknown, John Rackham, Ace Books, $0.60, 99+154 pages, dos, Omnibus)
Unknown. C.O.D. Mars / Alien Sea (Unknown, E. C. Tubb, Ace Books, $0.60, 99+154 pages, dos, Omnibus)