Cita APA (7th ed.)
Voegelin, C. F., & Voegelin, F. M. (1977). Classification and index of the world's languages. Elsevier.
Cita Chicago (17th ed.)
Voegelin, Charles Frederick, i Florence Marie Voegelin. Classification and Index of the World's Languages. New York, [usw.]: Elsevier, 1977.
Cita MLA (9th ed.)
Voegelin, Charles Frederick, i Florence Marie Voegelin. Classification and Index of the World's Languages. Elsevier, 1977.
Atenció: Aquestes cites poden no estar 100% correctes.