Rugpao, S., Amatayakul, K., Yutabootr, Y., Suwankiti, S., Sontirat, A., & Sethasathien, S. (1992). Vaginal Bleeding Patterns Among Lactating Women Using Contraceptive Methods. Thai Journal of Obstetrics and Gynaecology, 4(1), 33–41. retrieved from https://he02.tci-thaijo.org/index.php/tjog/article/view/257853