Divine, Robert A., author
New Viewpoints, 1974
Buku Teks
Buku Teks
edited by Robert W. Tucker, Charles B. Keely and Linda Wrigley
Westview Press, 1992
Buku Teks
Hunter, Robert E., author
Praeger, 1982
Buku Teks
edited by Barry M. Rubin and Elizabeth P. Spiro ; with a foreword by Muriel S. Humphrey
Westview Press, 1979
Buku Teks