Cita APA

Trussell, J. (1993). Natural family planning. Effective only if used perfectly.

Chicago Style Citation

Trussell, J. Natural Family Planning. Effective Only If Used Perfectly. 1993.

Cita MLA

Trussell, J. Natural Family Planning. Effective Only If Used Perfectly. 1993.

Atenció: Aquestes cites poden no estar 100% correctes.