Originally published: Hayes, Middlesex : Bran's Head Books Ltd., 1976.
"A Gollancz eBook."
OBNB doesn't sell books, but you may be able to find a copy at one of these websites:
Nebula maker by Olaf Stapledon. ISBN 9780575128705. Published by Gateway in 2013. Publication and catalogue information, links to buy online and reader comments.
