Columbia subject headings:
Kelles-Krauz, Kazimierz, 1872-1905.
Socialism.
Socialists--Poland--Correspondence.
Harvard subject headings:
Kelles-Krauz, Kazimierz, 1872-1905.
Socialism.
Socialists--Poland--Correspondence.
Princeton subject headings:
Socialism--Poland--History.
Socialists--Poland--Correspondence.