HOFFMAN, B. L. (2011). Williams Obstetrics Study Guide. Mc Graw- hill.
芝加哥风格引文HOFFMAN, Barbara L. Williams Obstetrics Study Guide. Mc Graw- hill, 2011.
MLA引文HOFFMAN, Barbara L. Williams Obstetrics Study Guide. Mc Graw- hill, 2011.
警告：这些引文格式不一定是100％准确.