Schweitzer, Stuart O., author
Oxford University Press, 2007
Buku Teks
Weinberg, Sandy, author
John Wiley & Sons, 2011
eBooks
Grebler, Leo
National Boreau of Economic Research , 1960
Buku Teks
Institute for Alternative Futures, 1983
Buku Teks
Tussing, Arlon R.
PennWell Books, 1995
Buku Teks