Ettinger, R, P., Golieb, D, E. (1962). Credits and collections (5th ed.). Englewood Cliffs, NJ: Prentice-Hall, c.
Ettinger, Richard, P.., Golieb, David, E.. "Credits and collections". 5th ed. Englewood Cliffs, NJ: Prentice-Hall, c, 1962. Buku Umum.