Heinlein Collections

  There is a collection called 6 X H, published by Pyramid Science Fiction, that is just The Unpleasant Profession of Jonathan Hoag by another name. Unless you're searching for utter compleatness in your collection, pick up one or the other, not both.

  The Past Through Tomorrow is a collection of all of the short stories that fit in Heinlein's Future History, which are also contained in other earlier collections, including The Man Who Sold the Moon, The Green Hills of Earth, Methuselah's Children, The Menace from Earth, and The Worlds of Robert A. Heinlein.