Zoltán Kodály's interest in Hungarian folk music began with his 1905 PhD thesis on the strophic form of Hungarian folk songs based, in part, on the early recordings of Béla Vikár. Kodály, along with Béla Bartók, began collecting folk music himself and later founded the Institute for Folk Music Research of the Hungarian Academy of Sciences. That institution has collected, transcribed, categorized, and systematized over 100,000 folk songs of the people of Hungary and of surrounding and related countries. The Corpus Musicae Popularis Hungaricae is the resulting published collection of these materials.