Nguyen USDT, Rothman KJ, Demissie S, Jackson DJ, Lang JM, Ecker JL. Transfers among women intending a birth center delivery in the San Diego birth center study. J Midwifery Womens Health. 2009 Mar 1;54(2):104-10.
Roberts J, Price J, Nelson LM, Burchinal M, Hennon E, Barnes B. Receptive vocabulary, expressive vocabulary, and speech production of boys with fragile X syndrome in comparison to boys with Down syndrome. Am J Ment Retard. 2007 May 1;112:177-93.