Yeung TW, Lee VC, Ng EH, Ho PC (December 2012). "A pilot study on the use of a 7-day course of letrozole followed by misoprostol for the termination of early pregnancy up to 63 days". Contraception. 86 (6): 763–769. doi:10.1016/j.contraception.2012.05.009. PMID22717187.
Lee VC, Ng EH, Yeung WS, Ho PC (February 2011). "Misoprostol with or without letrozole pretreatment for termination of pregnancy: a randomized controlled trial". Obstetrics and Gynecology. 117 (2 Pt 1): 317–23. doi:10.1097/AOG.0b013e3182073fbf. PMID21252745. S2CID25581158.
World Health Organization (2023). The selection and use of essential medicines 2023: web annex A: World Health Organization model list of essential medicines: 23rd list (2023). Geneva: World Health Organization. hdl:10665/371090. WHO/MHP/HPS/EML/2023.02.
Yeung TW, Lee VC, Ng EH, Ho PC (December 2012). "A pilot study on the use of a 7-day course of letrozole followed by misoprostol for the termination of early pregnancy up to 63 days". Contraception. 86 (6): 763–769. doi:10.1016/j.contraception.2012.05.009. PMID22717187.
Lee VC, Ng EH, Yeung WS, Ho PC (February 2011). "Misoprostol with or without letrozole pretreatment for termination of pregnancy: a randomized controlled trial". Obstetrics and Gynecology. 117 (2 Pt 1): 317–23. doi:10.1097/AOG.0b013e3182073fbf. PMID21252745. S2CID25581158.
Lee VC, Ng EH, Yeung WS, Ho PC (February 2011). "Misoprostol with or without letrozole pretreatment for termination of pregnancy: a randomized controlled trial". Obstetrics and Gynecology. 117 (2 Pt 1): 317–23. doi:10.1097/AOG.0b013e3182073fbf. PMID21252745. S2CID25581158.