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.
A very detailed description of the past, present, and future of the Alhambra including its history and stories concerning every single area of note within the domain of this city within a city. A great read before, during, and after a visit to the complex. Any guide is essential to the gaining of a complete understanding of the palace complex as you can learn about and see many different areas that may never be offered on a tour or walkabout.