Prince of Darkness

From Author Wars - https://authorwars.com/publications/prince-of-darkness-410740.html

Overview:

Title: Prince of Darkness
Author: Ray Russell
Year: 1971
ISBN-10: 0722175485
Publisher: Sphere
Price: 6/-
Pages: 157
Binding: Paperback
Type: Collection
Title Reference: Incommunicado
Notes: Price also stated: "30p". Other prices (back cover of Fantlab copy): Australia $1.00, New Zealand $1.00, South Africa 75¢, East Africa 7/25. Catalog #75485. Two stories "The Black Elixir" and "The Long Night" are under the group title "The Exploits of Argo".