APA

Spitz A. M., Ventura S. J., Koonin L. M., Strauss L. T., Frye A., Heuser R. L., Smith J. C., Morris L., Smith S. & Wingo P. (19940422). Surveillance for pregnancy and birth rates among teenagers, by state--United States, 1980 and 1990. : MMWR. CDC surveillance summaries : Morbidity and mortality weekly report. CDC surveillance summaries.

Chicago

Spitz A M, Ventura S J, Koonin L M, Strauss L T, Frye A, Heuser R L, Smith J C, Morris L, Smith S and Wingo P. 19940422. Surveillance for pregnancy and birth rates among teenagers, by state--United States, 1980 and 1990. : MMWR. CDC surveillance summaries : Morbidity and mortality weekly report. CDC surveillance summaries.

Harvard

Spitz A. M., Ventura S. J., Koonin L. M., Strauss L. T., Frye A., Heuser R. L., Smith J. C., Morris L., Smith S. and Wingo P. (19940422). Surveillance for pregnancy and birth rates among teenagers, by state--United States, 1980 and 1990. : MMWR. CDC surveillance summaries : Morbidity and mortality weekly report. CDC surveillance summaries.

MLA

Spitz A M, Ventura S J, Koonin L M, Strauss L T, Frye A, Heuser R L, Smith J C, Morris L, Smith S and Wingo P. Surveillance for pregnancy and birth rates among teenagers, by state--United States, 1980 and 1990. : MMWR. CDC surveillance summaries : Morbidity and mortality weekly report. CDC surveillance summaries. 19940422.