In a typical project, you'll most likely be generating your own content or soliciting original content from your user community.

However in some cases you may wish, or may feel that you need, to use third-party content, owned neither by yourself nor by your contributors). This may be text (e.g. museum catalogues, history book, web publications), images (e.g. from the web or scanned from books), or media such as video and audio clips. In such cases you will need to ensure that you do not plagiarise or infringe copyright. You should always make sure that you have read and understood the conditions of use; and you need to ensure (and document in your report) that explicit permission is given and, if necessary, requested from the owner(s) of the material that you intend to use. Terms and guidelines from, for example, a couple of image libraries are to be found at:

http://www.oldbookillustrations.com/articles.php?lng=en&pg=6
http://www.fromoldbooks.org/howto/
http://photoeverywhere.co.uk/image_use_terms.htm

and I'd encourage you to look at others.

A mark of a well-researched project, and of good project management, is that you've paid as much attention to IPR and other 'soft' issues as you pay to the 'product' you deliver.

Resources

Intellectual Property Issues in Cultural Heritage project
» http://en.wikipedia.org/wiki/Intellectual_property_issues_in_cultural_heritage_(IPinCH)

A few directories of free and public domain media are listed below:

Behold
A search engine for high-quality tagged Flickr images. Especially useful is the ability to constrain search to images that are free to use and modify.
» http://www.behold.cc

Creative Common Content Directories
» http://wiki.creativecommons.org/Content_Curators

Wikipedia:Public domain resources
» http://en.wikipedia.org/wiki/Wikipedia:Public_domain_resources

Wikipedia:Public domain image resources
» http://en.wikipedia.org/wiki/Wikipedia:Public_domain_image_resources

The Open Library
» http://www.openlibrary.org

Google Books
Around one-fifth of the books are free / public domain; the remainder covered by 'fair use' legislation
» http://books.google.com

Springfield Township High School Virtual Library
"Copyright-Friendly and Copyleft Images and Sound (Mostly!) for Use in Multimedia Projects and Web Pages"
» http://www.sdst.org/shs/library/cfimages.html

Library of Congress Map Collections
» http://memory.loc.gov/ammem/gmdhtml/gmdhome.html