City University of Hong Kong
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Screenshot of an e-book record in the Library catalogue

Demand Driven Acquisitions (DDA) model provides access to more e-books

To increase resource availability, the Library has adopted the Demand Driven Acquisitions (DDA) model in recent years to acquire e-books for the Library’s collection. Using this new acquisitions model, we gain access to thousands of English-language e-books while maximizing the Library’s purchasing power. DDA helps the Library to make the best use of its resources to meet the changing information needs of our users.

How does the DDA model work?

Unlike the traditional e-book selection process, the DDA model allows the Library to acquire an e-book title according to usage/demand. Thousands of new e-book records are added to our Library catalogue based on publishers or subjects. Additional titles are added regularly as the e-books are newly published. Students, faculty and staff members can access these new e-books for their research and educational needs.

Depending on the acquisitions model, the purchase of the e-book will be triggered if:

  1. It is browsed for a certain number of minutes or pages.
  2. It has been used frequently in a set period of time.

Currently, the Library has various DDA arrangements with publishers like Elsevier, Gale, Wiley, JSTOR, World Scientific Publishing and others.

What are the advantages of DDA?

Can I recommend titles in the traditional way?

Yes, you can still recommend titles via the Library catalogue at or send an email to