Heardman, h. (1987). Melahirkan secara alamiah (A way to natural childbirth). EGC.
芝加哥风格引文Heardman, helen. Melahirkan Secara Alamiah (A Way to Natural Childbirth). EGC, 1987.
MLA引文Heardman, helen. Melahirkan Secara Alamiah (A Way to Natural Childbirth). EGC, 1987.
警告：这些引文格式不一定是100％准确.