The Yoga Tradition, by Georg Feurstein – A must-have classic collection of yoga history, philosophy and practice in a mostly chronological rendering from the beginning to the end. Condensed translations of many yogic texts incorporated into the narrative discussion provides a real feel for the particular subject. If you want to know where and how your particular yoga practice fits into a larger context of “big yoga,” this is the book to begin with.
Yoga: The Art of Transformation, edited by Debra Diamond, the curated catalog for the 2013 exhibition at the Freer Gallery of Art of the Smithsonian Institution. A stunning art collection bringing yoga history, philosophy and practice to life, with excellent scholarly narratives to give a deeply grained context for the long history of yoga.
Any collection of teaching stories of Swami Kripalu – several are in publication now by John Mundahl and, of course, the original collection by Atma Jo Ann Levitt.
Asana and Mudra, by Swami Kripalu – his magnum opus work on yoga providing a look at his own practices and teachings about a deep practice of yoga.