Lougheed, Leslie Alan, author
Penguin Books, 1988
Buku Teks
by Les Rowntree ... [and others]
Prentice-Hall, 2011
Buku Teks
by Les Rowntree ... [and others]
Prenticel Hall, 2008
Buku Teks
Bryjak, George J
Allyn and Bacon, 1994
Buku Teks
The Conference Board; editor, Edward C. Bursk
The Free Press, 1973
Buku Teks