The three "Indexes to Early American Periodicals" cover three separate time periods from 1741 to 1935 and are thought to include all known periodical publications that had their inception and ending during this time period. In many cases Harvard has the originals of these periodicals. When the original copy is lacking, Harvard frequently has the microfilm copy derived from University Microfilms American Periodicals Series I, II, and III. Occasionally the microfilm is not owned locally but can be borrowed from the Center for Research Libraries (CRL) via Interlibrary Loan. Search titles in the HOLLIS Catalog in each case, or consult a Reference Librarian.