This is the "most complete rock encyclopedia ever published", issued as 99 separate fascicles, afterward re-grouped as 5 books.

Here we present the fascicle #28, from Roberta Flack (from page # 433) to Foundations (to page # 448).

Javier Marcote:

In this issue # 28 was included the cd Frank Zappa - My Guitar ("officially approved" being a bootleg).
It could be that in the next issue # 29 were the pages dedicated to Frank Zappa and a different cd announcing what could appear in the next fascicle ... or perhaps [the Zappa pages appeared] at the end of the collection with those fascicles dedicated to the "Z".
I think to remember when the 1st issue was published I bought it and there was a compilation of different groups and perhaps one of the themes were The Mothers.