Unknown, December 1940

From Author Wars - https://authorwars.com/publications/unknown-december-1940-61819.html

Overview:

Title: Unknown, December 1940
Author: John W. Campbell, Jr.
Year: 1940
Publisher: Street & Smith Publications, Inc.
Price: $0.20
Pages: 164
Binding: pulp
Type: MAGAZINE
Title Reference: Darker Than You Think
Notes: Volume IV, Number 4
No cover art. Interior art by Cartier and Isip.
Miller/Contento gives "Darker Than You Think" as a novel.