O`Sullivan, Aisling, author
CRC Press, 2017
Buku Teks
Lubbers, Ruud, author
Kluwer, 2008
Buku Teks
Bonillet, author
Paris Librairie Hachette et 1884
Buku Referensi
Weideman, Hugh
Thomas Y. Crowell Company, 1958
Buku Referensi
Cook, V. J.
Blackwell, 1997
Buku Teks