TYPED LETTER, SIGNED (TLS). 2 pages on 2 sheets, dated 13 June 1968, to Joel Frieman, on Analog Science Fiction / Science Fact letterhead. A fine letter entirely about the Street and Smith pulp UNKNOWN [later UNKNOWN WORLDS], a magazine edited by Campbell devoted entirely to fantasy. The magazine was published simultaneously with ASTOUNDING SCIENCE-FICTION, from the spring of 1939 to the fall of 1943. "The inception of UNKNOWN was, simply, that there were stories that were damn good stories -- which I couldn't print in ASTOUNDING, because they weren't science-fiction, and ASTOUNDING's readers invariably protested angrily if I ran fantasy. The solution seemed fairly plain -- start a new magazine ... UNKNOWN never lacked for reader-enthusiasm and reader-loyalty; it just lacked reader-numbers." 59 lines, approximately 500 words; good content. Fine. (#162848).