Publisher:Lancer

From ISFDB

A selection of 1961-70s Lancer covers are available at bookscans.com.

"Lancer Science Fiction Library" may be a publisher/publication series worth noting. E.g. Notes in this publication indicate there may have been two such series.

Lancer Science Fiction Library 1st Series 1962-65

Confirmed:
72-758 Transit Edmund Cooper
72-768 Divide and Rule L. Sprague de Camp
72-721 The Valley of Creation Edmond Hamilton
72-942 The Mindwarpers Eric Frank Russell
73-421 Darker Than You Think Jack Williamson
73-441 The Man Who Wanted Stars Dean McLaughlin
74-807 The Dying Earth Jack Vance
74-810 Recalled to Life Robert Silverberg
74-811 The Twenty-Second Century John Christopher
74-812 The Humanoids Jack Williamson
74-815 The Stars, Like Dust Isaac Asimov
74-816 The Currents of Space Isaac Asimov
74-819 Dreadful Sanctuary Eric Frank Russell

Suspected:
74-808 A Martian Odyssey and Other Classics of Science Fiction Stanley G. Weinbaum
74-818 The End of Eternity Isaac Asimov

Second series

Confirmed:
447-75385-095 Needle Hal Clement
447-75464-095 Robots Have No TailsHenry Kuttner

Suspected:
447-75422-095 Iceworld Hal Clement