Template:Ref-O'RahillyGardner1972
From Embryology
O'Rahilly R. and Gardner E. The initial appearance of ossification in staged human embryos. (1972) Amer. J. Anat., 7
O'Rahilly R. and Gardner E. The initial appearance of ossification in staged human embryos. (1972) Amer. J. Anat., 7