The easiest place I know are two references. The first is the Yale Catalog of Bright Stars by Hoffleit which lists the spectral types for over 6000 stars brighter than magnitude +6.3. The second is the Smithsonian Astrophysical Observatory Star Catalog which lists spectra for over 200,000 stars brighter than magnitude +9.0. Visit the National Space Science Data Center and get the Astronomical Catalogs CDROM which has both of these among many others.