Cowen, Zelman
Oxford University Press, 1959
Buku Teks
Wright, Charles Alan
West Publishing, [1983, ]
Buku Referensi
edited by Erica l. Dolgin and Thomas G.P. Guilbert
West Publishing, 1997
Buku Teks SO
Bittker, Boris I.
Little, Brown & Co., 1990
Buku Teks
Ferguson, John H.
McGraw-Hill, 1981
Buku Teks SO