"The present journal aims to be the locus for an unfolding of the problematic of communisation. It comes from the encounter of individuals involved in various projects in different countries: among these are the journals Endnotes, published in the UK and the US, Blaumachen in Greece, Théorie Communiste in France, Riff-Raff in Sweden, and certain more or less informal theoretical groups in the US (New York and San Francisco). Each of these projects will continue to exist on their own. Also participating are various individuals in France, Germany, and elsewhere, who are involved in other activities and who locate themselves broadly within the theoretical approach taken here."
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.
More readable than most communisation tracts but still had its moments. Neton and Åström’s essay on French bossnapping and Screamin’ Alice’s essay on the periodisation of the capitalist class relation were arguably the most concrete in their analyses - the others, not so much in my opinion.