APA (7 वां संस्करण) प्रशस्ति पत्र

Hagen, O. A. (2010). Digital books: Competition and commerce. Nova Science Publishers.

शिकागो शैली (17वां संस्करण) प्रशस्ति पत्र

Hagen, Oliver A. Digital Books: Competition and Commerce. New York: Nova Science Publishers, 2010.

एमएलए (9वां संस्करण) प्रशस्ति पत्र

Hagen, Oliver A. Digital Books: Competition and Commerce. Nova Science Publishers, 2010.