Ross, Susan Deller, author
Avon Books, 1973
Buku Teks
edited by Julie Peters and Andrea Wolper
Rouledge, 1995
Buku Teks
Hannay, Annie M.
U.S. Government Printing Office, 1953
Buku Teks
Artikel Jurnal
edited by Ian Brownlie, Guy S. Goodwin-Gill
Clarendon Press, 1971
Buku Teks