Doug Wilson, United States
"A classic: Peter F. Drucker, "Managing the Nonprofit Organization." (Available in audiobook as well.)
Also, Jim Collins' recent monograph "Good to Great and the Social Sectors: A Monograph to Accompany Good to Great" applies his five "Good to Great" concepts to the social sector.
Bobb Biehl and Ted Engstrom, "The Effective Board Member: Secrets of Making a Significant Contribution to Any Organization You Serve" -- originally published as "Increasing Your Boardroom Confidence.""