IMAGE+ is a monthly magazine featuring Image's upcoming releases, as well as bonus creator-owned comics content. Each issue features an original, four-page THE WALKING DEAD story concerning Negan's origins, and created by New York Times bestselling team ROBERT KIRKMAN and CHARLIE ADLARD, for a total of 48 pages of backstory! IMAGE+ showcases interviews, spotlight features, bonus never-before-seen preview pages, editorials from industry voices, and more in-depth, insightful and provocative comics coverage curated by David Brothers, Branding Manager at Image Comics. IMAGE+ is fans' premiere source for all things creator-owned.
Various is the correct author for any book with multiple unknown authors, and is acceptable for books with multiple known authors, especially if not all are known or the list is very long (over 50).
If an editor is known, however, Various is not necessary. List the name of the editor as the primary author (with role "editor"). Contributing authors' names follow it.
Note: WorldCat is an excellent resource for finding author information and contents of anthologies.