Hawtrey, R.G.
Longmas Green and Co. , 1952
Buku Teks
Pigou, A.
MacMillan, 1947
Buku Teks
edited by Victor R. Fuchs
University of Chicago, 1982
Buku Teks
edited by A.J. Culyer and K.G. Wright
Martin Robertson, 1978
Buku Teks
Lewis, William Arthur, author
University of Ghana by the Ghana Pub, 1971
Buku Teks