Columbia subject headings:
Ecology in literature.
Spanish literature--19th century--History and criticism.
Spanish literature--20th century--History and criticism.
Harvard subject headings:
Ecology in literature.
Spanish literature--19th century--History and criticism
Spanish literature--20th century--History and criticism
Princeton subject headings:
Ecology in literature.
Spanish literature--19th century--History and criticism.
Spanish literature--20th century--History and criticism.