Stebbins, Richard P., author
Harper & Row, 1963
Buku Teks
Bemis, Samuel Flagg, 1891-1973, author
Holt, Rinehart and Winston, 1965
Buku Teks
Simon and Schuster , 1945
Buku Teks
Stebbins, Richard P.
Harper & Brothers, 1955
Buku Teks
Pratt, Julius W., author
Prentice-Hall, 1965
Buku Teks