Neufeld, Meurice F.
Cornel University , 1961
Buku Teks
Buck, Solon Justus, author
Neb. University of Nebraska Press, 1965
Buku Teks
Fitzgerald, Walter, author
Methuen, 1952
Buku Teks
Basin-Yayim ve Turizm Bakanligi Yayinlarindan, 1961
Buku Teks
McDiarmid, Orville John, author
John Hopkins University Press, 1977
Buku Teks