Beattie, C. N., author
Stevens & Sons Lim. , 1957
Buku Teks
National Bureau of Economic Reserach, 1947
Buku Teks
Gaffney, Dennis J., author
McGraw-Hill, 1982
Buku Teks
Gaffney, Dennis J., author
McGraw-Hill, 1984
Buku Teks
Richards P.
Croom Helm, 1981
Buku Teks