Many newspapers, periodicals, and other historical materials remain accessible only in "microform" -- the generic term for microfilm and other micro-photographic technologies that became popular for preserving historical materials in the middle of the 20th c., and which remain in use today.

At the Yale Library, the following two search engines may prove useful in pointing to less known newspapers that have yet to be digitized:

• U.S. Newspapers on Microform
• International Newspapers on Microform