Linton, Ralph, 1893-1953, author
Appleton-Century-Crofts, 1936
Buku Teks
The Ronald Press Company, 1965
Buku Teks
Beals, Ralph L., author
Macmillan, 1977
Buku Teks
Beals, Ralph L., author
Macmillan, 1959
Buku Teks
Oliver, Chad
Harper & Row , 1981
Buku Teks