Cammack, Paul Anthony
Macmillan, 1993
Buku Teks
Ethridge, Marcus E.
Wadsworth and Cengage Learning, 2013
Buku Teks
David, Rene, 1906-
Stevens & sons, 1985
Buku Teks
Cox, Harvey G.
I.B. Tauris , 2009
Buku Teks SO
Zweigert, Konrad
Clarendon Press, 1998
Buku Teks