Unknown Fantasy Fiction, April 1941

From Author Wars - https://authorwars.com/publications/unknown-fantasy-fiction-april-1941-61816.html

Overview:

Title: Unknown Fantasy Fiction, April 1941
Author: John W. Campbell, Jr.
Year: 1941
Publisher: Street & Smith Publications, Inc.
Price: $0.20
Pages: 164
Binding: pulp
Type: MAGAZINE
Title Reference: They
Notes: Vol. IV No. 6
Subtitle "Fantasy Fiction" is shown only on the cover under "Unknown". All interior references are to "Street & Smith's Unknown.
Data from www.unz.org.
"The Castle of Iron" is called a novel on the contents page.