Covington, Howard E., Jr., author
Univesity of North Carolina Press, 1993
Buku Teks
Mueller, F. W.
McGraw-Hill Book Company, Inc., 1951
Buku Teks
Ranlett, John G., author
John Wiley & Sons, 1969
Buku Teks
Ranlett, John G., author
John Wiley & Sons, 1969
Buku Teks
Bradford, Frederick A., author
Longmans, Green, 1939
Buku Teks