reference materials on the design and commutation of switched reluctance motors.

Motorsoft motors has information on it's line of
switched reluctance motors including schematics and
performance information:

http://www.motorsoftmotors.com/sr.htm

The following link has ordering information on 
book "SWITCHED RELUCTANCE MOTORS AND THEIR CONTROLS" 
(ISBN:  1-881855-02-03).  This is from
the home page of the Magna Physics Publishing company:

http://www.magnaphysics.com/switched_reluctance_motors__and_.htm

From the page: "The aim of this book is to help engineers understand,
design and evaluate the switched reluctance motor (SRM) and its
controls."

Which appears to speak directly to you question.

I hope this helps.