Columbia subject headings:
Esperanto--History.
Zamenhof, L. L. (Ludwik Lazar), 1859-1917.
Harvard subject headings:
Esperanto--History.
Zamenhof, L. L. (Ludwik Lazar), 1859-1917.
Princeton subject headings:
Esperanto--History.
Zamenhof, L. L. (Ludwik Lazar), 1859-1917.