Buckley, E. A. (1961). How to increase sales with letters. McGraw Hill book company.
शिकागो स्टाइल उद्धरणBuckley, Earle A. How to Increase Sales with Letters. New York: McGraw Hill book company, 1961.
एमएलए उद्धरणBuckley, Earle A. How to Increase Sales with Letters. McGraw Hill book company, 1961.
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