Skidmore, Thomas E., author
Oxford University Press, 2001
Buku Teks
Rippy, J. Fred, author
University of Michigan Press, 1958
Buku Teks
Skidmore, Thomas E., author
Oxford University Press, 1984
Buku Teks
Meade, Teresa A., author
Wiley-Blackwell, 2010
Buku Teks
edited by Eduardo P. Archetti
MacMillan Education, 1987
Buku Teks