Mason, Alpheus Thomas,1899-1989
Prentice-Hall, 1959
Buku Teks
Routledge, 2000
Buku Teks
Deutsch, Kenneth L.
Thomson, 2009
Buku Teks
Scott, Andrew M.
Holt, Rinehart & Winston, 1959
Buku Teks
Wanlass, Lawrence C.
Appleton-Century-Crofts, 1953
Buku Teks