Beckman, T. N., & Foster, R. L. (1971). Credits and collections: Management and theory (8th ed.). Philippines copyright by McGraw-Hill Book Company.
Lua i Stíl Chicago (17ú heag.)Beckman, Theodore N., agus Roseann L. Foster. Credits and Collections: Management and Theory. 8th ed. New York: Philippines copyright by McGraw-Hill Book Company, 1971.
Lua MLA (9ú heag.)Beckman, Theodore N., agus Roseann L. Foster. Credits and Collections: Management and Theory. 8th ed. Philippines copyright by McGraw-Hill Book Company, 1971.
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