Columbia subject headings:
Hart, H. L. A. (Herbert Lionel Adolphus), 1907-1992.
Kelsen, Hans, 1881-1973.
Law--Philosophy.
Harvard subject headings:
Hart, H. L. A. (Herbert Lionel Adolphus), 1907-1992.
Kelsen, Hans, 1881-1973. Reine Rechtslehre.
Legal positivism.
Princeton subject headings: