McKenzie, Richard B., author
McGraw-Hill, 1978
Buku Teks
King, Victor T., author
RoutledgeCurzon, 2003
Buku Teks
Doran, Charles F., author
Free Press, 1977
Buku Teks
Brimmell, J. H.
Oxford University Press, 1959
Buku Teks
Wicksell, Knut
George Routledge and Sons , 1946
Buku Teks