Cunningham, F. Gary; Leveno, Kenneth J.; Bloom, Steven L.; Spong, Catherine Y.; Dashe, Jodi S.; Hoffman, Barbara L.; Casey, Brian M.; Sheffield, Jeanne S., eds. (2014). "Chapter 9: Prenatal Care". Williams obstetrics (24th ed.). New York: McGraw-Hill Education. Archived from the original on 31 December 2018. Retrieved 24 March 2022.
web.archive.org
Cunningham, F. Gary; Leveno, Kenneth J.; Bloom, Steven L.; Spong, Catherine Y.; Dashe, Jodi S.; Hoffman, Barbara L.; Casey, Brian M.; Sheffield, Jeanne S., eds. (2014). "Chapter 9: Prenatal Care". Williams obstetrics (24th ed.). New York: McGraw-Hill Education. Archived from the original on 31 December 2018. Retrieved 24 March 2022.
