Schilling, John W., author
American Management Association, 2008
eBooks
Barrett, John, author
Allen & Unwin, 1995
Buku Teks
Hardy, Thomas, 1840-1928, author
Macmillan Co. , 1947
Buku Teks
Anderson, Jessica, author
Viking, 1987
Buku Teks
editors, Ann Curthoys, A.W. Martin, Tim Rowse
Fairfax, Syme & Weldon Associates, 1987
Buku Referensi