The article presents an analysis of the main historical sources on the history of the People's Labor Union (NTS) in the Republic of Korea in the 1950s-1960s. The main attention is paid to such groups of sources as periodicals, ego-documents, speeches of NTS figures. The archival sources on the history of the NTS are analyzed, in particular, those stored in the Archives of the Center for Eastern European Studies, University of Bremen (Germany). The authors argue that a significant part of the sources on this topic are in the public domain and are not yet available to researchers.