Rogers, Margaret
Oceana Publications Inc., 1969
Buku Teks
edited by Hilary Lewis Ruttley
[publisher not identified], 1995
Buku Teks
Macneil, Ian R.
[publisher not identified], 1966
Buku Teks
Artikel Jurnal
Goode, Roy, author
Penguin Books, 2004
Buku Teks