Use the search box on the home page to search HOLLIS+ or HOLLIS Classic to locate books at any Harvard library. Both HOLLIS+ and HOLLIS Classic describes the more than 14 million volumes in the Harvard Library collections. There is a link to HOLLIS+ in the top right-hand corner of all of the library's web pages.
For more information about the differences between HOLLIS+ and HOLLIS Classic, review What's the difference? which is also linked from the search box on the home page.
Note that some materials are located at the Harvard Depository, a large, off-campus storage facility. Many of these items can be requested online through the HOLLIS Catalogs; other items will need to be requested through the library that owns the item. Items are generally delivered and available within one business day of a request.
If you don't find what you are looking for at Harvard, see Books Beyond Harvard.