Dave Marsh, For the Record 4: Sly and the Family Stone (1998)
Marsh writes that "There are two kinds of black music: before Sly Stone and after Sly Stone." Although he didn't get much information out of Sly Stone himself, this book is an up-close record of the rise and fall of the band based on first-hand accounts.
Joel Selvin, Smart Ass: The Music Journalism of Joel Selvin (2011)
This overview of Selvin's work includes a devastating essay on the untold story of the making of There's a Riot Goin' On, Sly and the Family Stone's 1971 follow-up to Stand!.
Jeff Kaliss, I Want to Take You Higher: The Life and Times of Sly and the Family Stone (2008)
A foreword by Sly Stone and a fascinating preface by George Clinton affirm the deep, first-hand research that went into this book.