Columbia subject headings:
Hartmann, Nicolai, 1882-1950.
Ontology--History--20th century.
Ontology.
Time--History--20th century.
Harvard subject headings:
Hartmann, Nicolai, 1882-1950
Hartmann, Nicolai, 1882-1950--Contributions in ontology.
Ontology--History--20th century.
Time--History--20th century.
Princeton subject headings:
Hartmann, Nicolai, 1882-1950--Criticism and interpretation.