1. Ajala MO, Oladipo OO, Afonja AO. Niger Postgrad Med J. 2001;8:16–21.
2. Asarian L, Geary NP. Trans R Soc. 2006;361:1251–63.
3. Augustine RA, Ladyman SR, Grattan DR. J Physiol 2008;586 (2):387–97.
4. Bealer SL, Lipschitz DL, Ramoz G, Crowley WR. Am J Physiol. 2006;291:R53–8.
5. Beall MH, El Haddad M, Gayle D, Desai M, Ross MG. Clin Obstet Gynecol. 2004;47:957–66.