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.
"I have never told this story, nor shall mortal man see this manuscript until I have passed over for eternity. I know that the average human mind will not believe what it cannot grasp......”
Written in 1912 this book is well written for its time and has intrigued countless generations of readers. I get the feeling that this story is being told over a campfire.
Captain Carter is telling the story from memory like an old man of his adventures here on Earth and on the planet of Barsoom (Mars). There are encounters with many strain creatures, situations, and yes even a "Princess of Mars.”
It is a tail worth reading as he encounters many creatures that are different personas of man, horse, dog, etc.
This book also titled “Under The Moons Of Mars” is a part of a series by the writer that brought us “Tarzan.” The intro to the book alone will capture your imagination.