Ritchie, J.B.
West Publshing Company, 1980
Buku Teks
edited by Mason Haire
John Wiley & Sons, 1959
Buku Teks
Hatch, Mary Jo.
Oxford University Press , 2013
Buku Teks
Thompson, James D.
McGraw-Hill, 1967
Buku Teks
Miles, Robert H.
Goodyear Publishing Company, 1980
Buku Teks