Masters of the Vortex

From Author Wars - https://authorwars.com/publications/masters-of-the-vortex-993833.html

Overview:

Title: Masters of the Vortex
Author: E. E. 'Doc' Smith
Year: 1978
ISBN-10: 0586038485
Publisher: Panther / Granada
Price: £0.75
Pages: 192
Binding: Paperback
Type: Novel
Title Reference: Masters of the Vortex
Notes:
- On title page:
  - Masters of the Vortex
  - (original title: The Vortex Blaster)
  - The seventh novel of the Lensman series
- On copyright page:
  - Published by Granada Publishing Limited in Panther Books 1973
  - Reprinted 1973, 1976, 1978
- "Panther" on front cover but "Panther Granada" elsewhere in book, including title page
- Publisher assigns this story to Lensman series but ISFDb assigns it to Vortex Blaster series, part of the Lensman Universe
- 10 digit ISBN on copyright page; 9 digit SBN on front and rear covers
- Cover artist not credited; no visible signature
- Cover artist credited in Hardware: The Definitive SF Works of Chris Foss
- Other prices: Canada $2.25, Australia $2.15, New Zealand $2.35