Whitworth, M; Bricker, L; Neilson, JP; Dowswell, T (2010). "Ultrasound for fetal assessment in early pregnancy". Cochrane Database of Systematic Reviews (4): CD007058. doi:10.1002/14651858.CD007058.pub2. PMID20393955.
Whitworth, M; Bricker, L; Neilson, JP; Dowswell, T (2010). "Ultrasound for fetal assessment in early pregnancy". Cochrane Database of Systematic Reviews (4): CD007058. doi:10.1002/14651858.CD007058.pub2. PMID20393955.
nlm.nih.gov
"Miscarriage". A.D.A.M., Inc. 21 Nov 2010. สืบค้นเมื่อ 28 February 2012.