Columbia subject headings:
Harvard subject headings:
Esperanto.
Language, Universal.
Languages, Artificial.
Wiener, Leo, 1862-1939
Zamenhof, L. L. (Ludwik Lazar), 1859-1917.
Princeton subject headings:
Esperanto.
Language, Universal.
Languages, Artificial.
Wiener, Leo, 1862-1939.
Zamenhof, L. L. (Ludwik Lazar), 1859-1917.