Sprague, E. (1961). What Is Philosophy? Oxford University Press.
Cita Chicago (17th ed.)Sprague, Elmer. What Is Philosophy? New York: Oxford University Press, 1961.
Cita MLA (9th ed.)Sprague, Elmer. What Is Philosophy? Oxford University Press, 1961.
Atenció: Aquestes cites poden no estar 100% correctes.