Columbia subject headings:
Harvard subject headings:
Bulgaria--Relations--Macedonia.
Bulgaria--Relations--Serbia.
Ethnology--North Macedonia--Congresses.
Ethnology--Serbia--Morava River Region--Congresses.
Macedonia--Relations--Bulgaria.
Serbia--Relations--Bulgaria.
Princeton subject headings:
Bulgaria--Relations--Macedonia.
Bulgaria--Relations--Yugoslavia--Serbia.
Ethnology--Macedonia.
Ethnology--Yugoslavia--Morava River Region (Serbia).
Macedonia--Relations--Bulgaria.
Macedonian question.
Serbia--Relations--Bulgaria.