Cassingham KM, Sills EO, Pattanayak SK, Mansfield CA. Voluntary conservation of North Carolina's natural heritage. J For. 2002;100(5):16-23.
Sorensen HT, Steffensen FH, Sabroe S, Rothman KJ, Gillman MW, Fischer P. Historical cohort study of in utero exposure to uterotonic drugs and cognitive function in young adult life. West J Med. 1999 Jan 1;170(5):260-2.