Just adding my bit from kellymom about the people who recommend solids 6months+.
I thought people could use this info in any emails/letters:

The following organizations recommend that all babies be exclusively breastfed (no cereal, juice or any other foods) for the first 6 months of life (not the first 4-6 months):

World Health Organization
UNICEF
US Department of Health & Human Services
American Academy of Pediatrics
American Academy of Family Physicians
American Dietetic Association
Australian National Health and Medical Research Council
Royal Australian College of General Practitioners
Health Canada