The Dark Is Rising

From Author Wars - https://authorwars.com/books/the-dark-is-rising-914821.html

Overview:

Title: The Dark Is Rising
Author: Susan Cooper
Year: 1996
Type: Omnibuses

Editions/Publications:

Unknown. The Dark Is Rising (Unknown, Susan Cooper, GuildAmerica Books / SFBC, ISBN-10: 1568652054, $14.98, 865 pages, Hardcover, Omnibus)