B. Lang Jeffrey. (1994). The American express guide to corporate travel management (In lần thứ 1.). American: Amacom.
शिकागो स्टाइल उद्धरणB. Lang Jeffrey. The American Express Guide to Corporate Travel Management. In lần thứ 1. American: Amacom, 1994.
एमएलए उद्धरणB. Lang Jeffrey. The American Express Guide to Corporate Travel Management. In lần thứ 1. American: Amacom, 1994.
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