Columbia subject headings:
Anarchism--United States--History--20th century.
Education--United States--Experimental methods--History--20th century.
Education--United States--Philosophy--History--20th century.
Educators--Political activity--United States--History--20th century.
Ferrer Guardia, Francisco, 1859-1909.
Harvard subject headings:
Anarchism--United States--History--20th century.
Education--United States--Experimental methods--History--20th century.
Education--United States--Philosophy--History--20th century.
Educators--Political activity--United States--History--20th century.
Educators--United States--Political activity--History--20th century.
Ferrer Guardia, Francisco, 1859-1909.
Princeton subject headings:
Anarchism--United States--History--20th century.
Education--United States--Experimental methods--History--20th century.
Education--United States--Philosophy--History--20th century.
Educators--United States--Political activity--History--20th century.
Ferrer Guardia, Francisco, 1859-1909.