Columbia subject headings:
Literature, Modern--19th century--History and criticism.
Literature, Modern--20th century--History and criticism.
Sleep in literature.
Harvard subject headings:
Literature, Modern--19th century--History and criticism
Literature, Modern--20th century--History and criticism
Sleep in literature.
Princeton subject headings:
Literature, Modern--19th century--History and criticism.
Literature, Modern--20th century--History and criticism.
Sleep in literature.