For example, on this book: http://www.biblio.gs/book/48238-Threat-By-Example-A-Documentation-Of-Inspiration
The front cover says "Words and Art From: ... The Ex" though the article inside is written by G.W. Sok (of the band): http://www.biblio.gs/credit/48246-G-W-Sok
I've credited: Contributor G.W. Sok
Is this the best way to go about it? Or should the credit go to "The Ex"?
credits as on release I think, any interpretation of them can go in notes
I agree with maldoror. In this case, a musical band is no different in theory than a publishing company, a design group or even a collective of authors. It's a group of people gathered for one common cause.
OK, "as on release" makes sense for the most part.
In the above example, the chapter has a brief introduction by the compiler of the book, which includes the text "The following essay was written by the band's vocalist, G.W. Sok." Would the proper credits be:
Contributor: The Ex
Writer: G.W. Sok
could be Text by and Artist for the band, if the exact credits are not in the list there are many that could fit