Elsevier, 1973
Buku Teks
Chorafas, Dimitris N., author
Reinhold Publishing Corporation, 1958
Buku Teks
edited by Joseph F. McCloskey, Florence N. Trefethen
John Hopkins Press, 1954
Buku Teks
Gummesson, Evert
Sage Publications, Inc., 2000
Buku Teks
Howard, Keith, author
MCB University Press, 1990
Buku Referensi