Okun, B. (1958). Trends in birth rates in the United States since 1870. Johns Hopkins Press.
Cita Chicago (17th ed.)Okun, Bernard. Trends in Birth Rates in the United States Since 1870. Baltimore: Johns Hopkins Press, 1958.
Cita MLA (9th ed.)Okun, Bernard. Trends in Birth Rates in the United States Since 1870. Johns Hopkins Press, 1958.
Atenció: Aquestes cites poden no estar 100% correctes.