Cover artist: Edward Valigursky (1926 - 2009) The 13th Immortal by Robert Silverberg, 1957

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Cover artist: Edward Valigursky (1926 - 2009) The 13th Immortal by Robert Silverberg, 1957
Art by Tim Hildebrandt for Those Who Watch by Robert Silverberg (1987, acrylic on Masonite)
The Second Trip - art by Dan Adkins (1971)
Cover illustration by Don Punchatz
Info from ISFDB
Beautiful front cover art by Ron Walotsky for Silverberg's Up the Line... and then there's the back cover as well. I know Silverberg is well known for this kind of Silverberg stuff, but it still gets me shaking my head.
Robert Silverberg, RÉSURRECTIONS [RECALLED TO LIFE] (Marabout, 1974), with cover art by Henri Lievens.
Robert Silverberg - Born With The Dead - Coronet - 1975 (cover illustration by Jim Burns)
Earth's Other Shadow by Robert Silverberg, cover by Colin Hay (1978)