1. American heritage dictionary of the English language,2000
2. Parity and pregnancy outcomes;Bai;American Journal of Obstetrics and Gynecology,2002
3. Williams obstetrics;Cunningham,2001
4. Dorland’s illustrated medical dictionary,2002
5. Quality of data on subsequent events in a routine medical birth register;Gissler;Medical Informatics and the Internet in Medicine,2002