Abel, Darrel, author
Barron's Educational Series, 1963
Buku Referensi
Hart, James, author
Oxford University Press, 1948
Buku Teks
Bendixen, Alfred, author
Wiley-Blackwell, 2010
Buku Teks
Short, Raymond W., author
Henry Holt and Company, 1954
Buku Teks
Wachner, Clarence W., author
Macmillan, 1963
Buku Teks