Macgregor, D.H., author
Oxford University Press, 1949
Buku Teks
edited by David Greenaway, Michael Bleaney, and Ian Stewart
Routledge, 1991
Buku Referensi
Kirzner, Israel M., author
D. Van Nostrand , 1960
Buku Teks
Wilhite, Virgle Glenn
Bookman Associates , 1958
Buku Teks
Roll, Eric
Prentice-Hall, 1959
Buku Teks