I’ve been reading The Woodwind Player’s Cookbook, published last year by Meredith Music and edited by Charles West. It’s a collection of 57 pedagogical essays by a pretty impressive roster of woodwind folks. You can download the table of contents here to see the authors and titles.
Most of the articles deal with technique fundamentals on specific instruments, which should make this book valuable to school band directors, but it also works quite well as a handbook for woodwind doublers; in fact, there are several articles that deal specifically with doubling, by Mike Duva, James Nesbit, Elsie Parker, and Albert Regni.