Higgins, Benjamin
Richard D. Irwin, 1962
Buku Teks
University of Queensland, 1974
UI - Disertasi (Membership)
Buku Teks
edited by Robert W. Tucker, Charles B. Keely and Linda Wrigley
Westview Press, 1992
Buku Teks
Randall, Clarence B.
The University of Chicago Press, 1954
Buku Teks