Columbia subject headings:
Pérez de Ayala, Ramón, 1880-1962--Criticism and interpretation.
Pérez de Ayala, Ramón, 1880-1962--Philosophy.
Harvard subject headings:
Pérez de Ayala, Ramón, 1880-1962--Criticism and interpretation.
Pérez de Ayala, Ramón, 1880-1962--Philosophy.
Princeton subject headings:
Pérez de Ayala, Ramón, 1880-1962--Criticism and interpretation.