"Journal of Perinatal Medicine - Official Journal of the WAPM", 21.6 (1993): 419-506. Retrieved 22 May. 2013, from http://www.degruyter.com/view/j/jpme.1993.21.issue-6/issue-files/jpme.1993.21.issue-6.xml

Journal of Perinatal Medicine - Official Journal of the WAPM (1993), 21(6), pp. 419-506. Retrieved 22 May. 2013, from http://www.degruyter.com/view/j/jpme.1993.21.issue-6/issue-files/jpme.1993.21.issue-6.xml

Journal of Perinatal Medicine - Official Journal of the WAPM. 1993. 21(6): 419-506. Retrieved 22 May. 2013, from http://www.degruyter.com/view/j/jpme.1993.21.issue-6/issue-files/jpme.1993.21.issue-6.xml