Hamilton, Robert W.
St. Paul, Minn, 1989
Buku Teks
Burtchett, Floyd Franklin
Clifford Milton, 1964
Buku Teks
Hamilton, Robert W.
West Publishing, 1984
Buku Teks SO
Husband, William H.
Richard D. Irwin, 1948, 1955, 1962
Buku Teks SO
Masson, Robert L.
McGraw-Hill, 1935
Buku Teks SO