Cita APA (7th ed.)
ebrary, Inc, & Hagen, O. A. (2010). Digital books: Competition and commerce. Nova Science Publishers.
Cita Chicago (17th ed.)
ebrary, Inc, i Oliver A. Hagen. Digital Books: Competition and Commerce. [Hauppauge, N.Y.]: Nova Science Publishers, 2010.
Cita MLA (9th ed.)
ebrary, Inc, i Oliver A. Hagen. Digital Books: Competition and Commerce. Nova Science Publishers, 2010.
Atenció: Aquestes cites poden no estar 100% correctes.