These outside resources are helpful aids for conducting research or looking for a tale.
SurLaLune is a collection of organized and annotated fairy tales, found here
SurLaLune Folklore Database provides organized lists of tales and books, with some detail about ATUs. Tales can be read directly on the webpage, which can be found here
University of Missouri Libraries has a helpful guide to the ATU index, which lists different tale types with their characterizing features, as well as gives example tales. It can be found here