Craig, Paul
Clarendon Press, 1995
Buku Teks
Vagts, Detlev F., author
The Foundation Press, INC, 1973
Buku Teks
Schlesinger, Rudolf B.
Stevens & Sons , 1960
Buku Klasik
Schlesinger, Rudolf B.
The Foundation Press, Inc., 1959
Buku Klasik
Bossche, Peter van den, author
Cambridge University Press, 2017
Buku Teks