Columbia subject headings:
Bŭlgarska komunisticheska partii︠a︡.
Bŭlgarska rabotnicheska sot͡sialdemokraticheska partii͡a (tesni sot͡sialisty)
Bŭlgarska rabotnicheska sot︠s︡ialdemokraticheska partii︠a︡.
Communism--Bulgaria--History--Sources.
Harvard subject headings:
Bŭlgarska komunisticheska partii︠a︡--History--Sources.
Bŭlgarska rabotnicheska sot︠s︡ialdemokraticheska partii︠a︡--History--Sources.
Labor movement--Bulgaria--Burgas (District)
Princeton subject headings: