Cita APA

Billings, J. J. (1993). Natural family planning. Natural methods have cross cultural appeal.

Chicago Style Citation

Billings, J J. Natural Family Planning. Natural Methods Have Cross Cultural Appeal. 1993.

Cita MLA

Billings, J J. Natural Family Planning. Natural Methods Have Cross Cultural Appeal. 1993.

Atenció: Aquestes cites poden no estar 100% correctes.