1. Vital Statistics of the United States, Volume 1, Natality. Annual Volumes, National Center for Health Statistics, U.S. Department of Health, Education, and Welfare.
2. Prevention of low birth weight and pre-term birth;Hemminki,1978
3. An epidemiologic study of preterm delivery;Berkowitz;Am J Epidemiol,1981
4. Clinical assessment of gestational age in the newborn infant;Dubowitz;J Pediatr,1970
5. The social readjustment rating scale;Holmes;J Psychosom Res,1967