@book{ BA13424626, author = "Williams, J. Whitridge (John Whitridge) and Cunningham, F. Gary and MacDonald, Paul C. and Gant, Norman F.", title = "Williams obstetrics", publisher = "Prentice-Hall International", year = "1989", edition = "18th ed. / F. Gary Cunningham, Paul C. MacDonald, Norman F. Grant", URL = "https://ci.nii.ac.jp/ncid/BA13424626" }