The Economist
Economist Books, 1992
Buku Referensi
Hubbard, Douglas W., author
Wiley, 2014
Buku Teks
Hubbard, Douglas W., author
John Wiley & Sons, 2007
Buku Teks
edited by Dennis Upper, Joseph R. Cautela
Pergamon Press , 1979
Buku Teks
Morris, Deborah Gray, author
Mosby Elsevier , 2010
Buku Teks