Columbia subject headings:
Harvard subject headings:
Historians--Poland--Biography
Poland--Politics and government--1918-1945
Polska Partia Socjalistyczna--Biography.
Próchnik, Adam.
Statesmen--Poland--Biography.
Princeton subject headings:
Politicians--Poland--Biography.
Polska Partia Socjalistyczna--Biography.
Próchnik, Adam.
Socialists--Poland--Biography.