Childhood Immunization Information Page
www.nlm.nih.gov/medlineplus/childhoodimmunization.html
National Library of Medicine, MedlinePlus

Frequently Asked Questions About Immunizations
http://www.kidshealth.org/PageManager.jsp?
dn=columbuschildrens&article_set=22913&lic=238&cat_id=189
KidsHealth for Parents by Nationwide Children's Health e-Hints