International standards for early fetal size and pregnancy dating based on ultrasound measurement of crown–rump length in the first trimester of pregnancy

by Papageorghiou, A T, Kennedy, S H, Salomon, L J, Ohuma, E O, Cheikh Ismail, L, Barros, F C, Lambert, A, Carvalho, M, Jaffer, Y A, Bertino, E, Gravett, M G, Altman, D G, Purwar, M, Noble, J A, Pang, R, Victora, C G, Bhutta, Z A, Villar, J
Published 2014