Kohler, Heinz, author
Dryden Press, 1970
Buku Teks
Boulding, Kenneth E. (Kenneth Ewart), 1910-1993, author
Tata McGraw-Hill, 1970
Buku Teks
Atkinson, Lloyd C., author
Richard D. Irwin, 1982
Buku Teks
Kohler, Heinz
Holt, Rinehart and Winston, 1968
Buku Teks
edited by Michael E. Soule
Sinauer Associates, 1986
Buku Teks