Headway is for students who want to use English accurately and fluently, and to communicate with ease in both social and everyday situatiuons. This latest addition to the Headway family offers the beginner and false beginner all the best features of the Headway package plus the newer features of `Everyday English' sections, an integrated vocabulary syllabus, and revision and self-access sections after every four units.
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.