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.
Great book to get ideas from to make all sorts of cards. I learned that using punches you can make apertures, borders or sponge around the punched-out motif. Few nice projects for silk ribbon embroidery (with templates included). I also liked the look of card and thread. Some clever watercolour techniques are explained. Who knows maybe I'll give quilling a go although I think it might be a little tricky. Great tips on making 3D cards; never realised you have to use a craft knife (10A blade on self-healing cutting mat) Nor that you could "shape" the paper to enhance the 3-D effect or that you could colour in the edges with a pencil. The project I most liked from this book is the iris folding card with the pot plant.