Williams, H. S. (1914). Twilight sleep: A simple account of new discoveries in painless childbirth. Harper.
Chicago-referens (17:e uppl.)Williams, Henry Smith. Twilight Sleep: A Simple Account of New Discoveries in Painless Childbirth. New York: Harper, 1914.
MLA-referens (8:e uppl.)Williams, Henry Smith. Twilight Sleep: A Simple Account of New Discoveries in Painless Childbirth. Harper, 1914.
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