This collection originally published: in 1 vol. Reading, Pa. : Fantasy Press, 1953 ; London : Museum Press, 1955.
OBNB doesn't sell books, but you may be able to find a copy at one of these websites:
Assignment in eternity by Robert A. Heinlein. ISBN 0450037592. Published by New English Library in 1978. Publication and catalogue information, links to buy online and reader comments.
