Modes of Science Fiction

From Author Wars - https://authorwars.com/books/modes-of-science-fiction-1462108.html

Overview:

Title: Modes of Science Fiction
Author: Jack Williamson
Year: 1968
Type: Essays

Editions/Publications:

Unknown. At the Human Limit (Unknown, Jack Williamson, Haffner Press, ISBN-10: 9781893887527, $150.00, xxi+590 pages, Hardcover, Collection)
2011 . At the Human Limit (2011, Jack Williamson, Haffner Press, ISBN-10: 9781893887510, $40.00, xxi+590 pages, Hardcover, Collection)