edited by Richard C. Vetter
Voice of America, 1974
Buku Teks
Weyl, Peter K.
John Wiley & Sons, 1970
Buku Teks
Yasso, Warren E.
New York: Holt, Rinehart and Winston, 1965
Buku Teks
Yasso, Warren E.
New York: Holt, Rinehart and Winston, 1965
Buku Teks
Carson, Rachel L.
A Mentor Book, 1954
Buku Teks