Wilcox AJ, Baird DD, Weinberg CR. 1999. Time of implantation of the conceptus and loss of pregnancy. New England Journal of Medicine. 340 (23): 1796–1799. doi:10.1056/NEJM199906103402304. PMID10362823
Wilcox AJ, Baird DD, Weinberg CR. Lipanj 1999. Time of implantation of the conceptus and loss of pregnancy. New England Journal of Medicine. 340 (23): 1796–9. doi:10.1056/NEJM199906103402304. PMID10362823
Waddell, Rebecca Smith. 2006. FertilityPlus.org. Home Pregnancy Test hCG Levels and FAQ. Inačica izvorne stranice arhivirana 15. lipnja 2006. Pristupljeno 17. lipnja 2006.
Wilcox AJ, Baird DD, Weinberg CR. 1999. Time of implantation of the conceptus and loss of pregnancy. New England Journal of Medicine. 340 (23): 1796–1799. doi:10.1056/NEJM199906103402304. PMID10362823
Wilcox AJ, Baird DD, Weinberg CR. Lipanj 1999. Time of implantation of the conceptus and loss of pregnancy. New England Journal of Medicine. 340 (23): 1796–9. doi:10.1056/NEJM199906103402304. PMID10362823
Waddell, Rebecca Smith. 2006. FertilityPlus.org. Home Pregnancy Test hCG Levels and FAQ. Inačica izvorne stranice arhivirana 15. lipnja 2006. Pristupljeno 17. lipnja 2006.