Billings, E., & Westmore, A. (2007). Metode Ovulasi Billing. Cara Mengatur Kesuburan. KPG.
Chicagoスタイル(17版)引用形式Billings, Evelyn, , Ann Westmore. Metode Ovulasi Billing. Cara Mengatur Kesuburan. KPG, 2007.
MLA(9版)引用形式Billings, Evelyn, , Ann Westmore. Metode Ovulasi Billing. Cara Mengatur Kesuburan. KPG, 2007.
警告: この引用は必ずしも正確ではありません.