Cleveland, Ohio, Lincoln Extension Institute
Buku Teks
Ian Beardwell, Len Holden
Prentice-Hall, 2001
Buku Teks
Fitz-enz, Jac, author
McGraw-Hill, 2001
Buku Teks
Randall S.Schuler, Susan E.Jackson, editor
Blackwell Publisher, 2000
Buku Teks
Mike Millmore, Philip Lewis, Mark Saunders, Adrian Thornhill, Trevor Morrow
Prentice-Hall, 2007
Buku Teks