By far the best index for finding magazine articles is this self-contained microfilm display available for use in most libraries.
It’s the size of a regular microfiche reader but with only one filmstrip roll, which the libraries update monthly or bimonthly. Unlike the Reader’s Guide to Periodical Literature, it’s a one-stop magazine index — you don’t have to keep going from volume to volume. It indexes 400 magazines back six years, with supplements on fiche going back to 1977.