The chapter in the professional book reflects the research activities of Jan Trojan (1926-2015). He clarifies the methodological basis of his music-historiographic research and analyzes the specifics of his research in the field of folklore and music journalism. Trojan first profiled himself as a music historian, who was mainly interested in the music of the Moravian region of the 17th - 19th centuries, but soon his interest spread to Moravian folklore in general: his first published book in 1980 was Moravian Folk Song. One of the most important chapters in his work is the edition of Leoš Janáček: he prepared 16 Janáček's compositions for publication in Supraphon 1970-1980, on the other hand he devoted himself to archival research and publishing compositions by old Czech composers of the 17th-19th centuries. He also worked as an erudite publicist and critic in the daily and professional press.