1. Labour pain: The role of childbirth education, information and expectation;Astbury,1980
2. Ethnicity and pain: A biocultural model;Bates;Social Science and Medicine,1987
3. Effects of analgesia on labor;Berg;Clinical Obstetrics and Gynecology,1992
4. Anatomic and physiologic basis of nociception and pain;Bonica,1990
5. Definitions and taxonomy of pain;Bonica,1990