Dyfyniad APA

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

Dyfyniad Arddull Chicago

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

Dyfyniad MLA

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

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