Wallacem W. Stewart
Macmillan, 1945
Buku Teks
[publisher not identified], [date of publication not identified]
Buku Teks
Wallace, W. Stewart, author
Macmillan, 1945
Buku Referensi
edited by Thomas M. Paikeday
Holt, Rinehart and Winston, 1976
Buku Referensi
Charles Scribner's Sons, 1964
Buku Referensi