Researchers Aarne, Thompson, and Uther developed the "ATU" classification system in order to group like tales together and to distinguish between variants. The 3-volume downloadable set linked below is the authoritative bibliography of the ATU system. The research cited for each type includes documentation of its international distribution, as well as monographic works or articles on that type. A detailed subject index includes the most important subjects, actions, and other motifs, including actors and settings. Access provided courtesy of the Kalevala Society Foundation and Folklore Fellows' Communications (FFC).