APA (7th ed.) Citation

Sher, D., & Sher, M. (1999). How to collect debts and still keep your customers. Amacom.

Chicago Style (17th ed.) Citation

Sher, David, and Martin Sher. How to Collect Debts and Still Keep Your Customers. New York: Amacom, 1999.

MLA (9th ed.) Citation

Sher, David, and Martin Sher. How to Collect Debts and Still Keep Your Customers. Amacom, 1999.