Dutch artist Mark Manders - who will represent the Netherlands at the 55th Venice Biennale in 2013 - was awarded the Heineken Prize for Art 2012. The jury praised him "for his ability to create a personal world with a distinct visual language that both intrigues and becomes fixed in the memory." On the occasion of this award, Roma Publications compiled this almost encyclopedic book which covers Manders' entire oeuvre from the late 1980s until the present. It contains facsimiles of the artist's publications and a focus on a large number of recent, never-published works.
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.