Columbia subject headings:
Abortifacients--Research.
Mifepristone--Research.
Progesterone--Antagonists--Research.
Harvard subject headings:
Abortifacients--Research.
Mifepristone--Research.
Progesterone--Antagonists--Research.
Princeton subject headings:
Abortifacients--Research.
Mifepristone--Research.
Progesterone--Antagonists--Research.