Harthan, John, author
Thame and Hudson, 1981
Buku Referensi
Kenny, Anthony, author
Blackwell Publishing, 2007
Buku Teks
Weber, Eugen, author
D.C. Heath, 1959
Buku Teks
Weber, Eugen, author
D. C. Heath, 1959
Buku Teks
Naidis, Mark, author
Dryden Press, 1972
Buku Teks