Lower, Arthur R.M.
The Ryerson Press, 1952
Buku Teks
Siegel, Eric S.
John Wiley & Sons, 1987
Buku Teks
Lower, Arthur R.M.
Longmans, Green and Company, 1959
Buku Teks
Lower, Arthur R.M.
Longmans, Green and Company, 1958
Buku Teks
Holcombe, Arthur N.
Harvard University Press, 1940
Buku Teks