http://www.cirp.org/library/birth/ (links to medical articles and positional papers)
Dr. Momma compiled resources on circumcision and breastfeeding:
Circumcision and Breastfeeding: Authoritative, medical citations are provided, divided by the type of disruption caused by circumcision.
Letters to La Leche League International. Leaven. Vol. 36 no. 5. October November 2000. pp. 94-95
The Breastfeeding Answer Book (Third Revised Edition) by Nancy Mohrbacher, IBCLC, Julie Stock, MA, IBCLC. La Leche League International, Schaumburg, Illinois, 2003.