Wood, A.W.
Mouton, 1974
Buku Teks
Artikel Jurnal
edited by Christian P. Potholm and Richard A. Fredland
University Press of America, 1980
Buku Teks
Macneil, Ian R.
[Publisher not identified], 1966
Buku Teks
Clark, Wilfrid E. Le Gros
Holt, Rinehart and Winston, 1967
Buku Teks