White, N.D.
Manchester University Press, 1993
Buku Teks
Kirgis, Frederic L.
West Publishing, 1993
Buku Teks
edited by Evan Luard
Praeger, 1966
Buku Teks
Edwards, Paul M.
Paul M. Edwards, 2006
Buku Referensi
Peaslee, Amos J.
Martinus Nijhoff, 1956
Buku Teks