Columbia subject headings:
American poetry--20th century--History and criticism.
Free verse.
Literature and morals.
Harvard subject headings:
American poetry--20th century--History and criticism
English language--20th century--Versification.
English language--Versification
Experimental poetry, American--History and criticism.
Literature and morals--History--20th century.
Literature and morals.
Princeton subject headings:
American poetry--20th century--History and criticism.
English language--Versification.
Literature and morals.