Berkley Medallion, 1970 (this printing from 1972). Cover artist unknown. [More info on ISFDB]
From Wikipedia:
Stranger in a Strange Land is a 1961 science fiction novel by American author Robert A. Heinlein. It tells the story of Valentine Michael Smith, a human who comes to Earth in early adulthood after being born on the planet Mars and raised by Martians, and explores his interaction with and eventual transformation of Terran culture. […]
Stranger in a Strange Land won the 1962 Hugo Award for Best Novel and became the first science fiction novel to enter The New York Times Book Review’s best-seller list. In 2012, the Library of Congress named it one of 88 “Books that Shaped America”.
Shown here are two covers for Berkley’s paperback edition of “the best-selling underground novel by the dean of American science fiction writers.” The one depicted below came first, in 1968. In 1970, it was superseded by a new design, albeit with the same typography.
When used in caps, Karlgeorg Hoefer’s Permanent Headline (1964) can look a lot like Walter Haettenschweiler’s Schmalfette Grotesk (1954). It’s not quite as round, and the spine in S is less steep. Compare Schmalfette Grotesk to Permanent Headline.
Berkley Medallion, March 1968, with cover art by Paul Lehr. [More info on ISFDB]