Cita APA (7th ed.)
Gustavson, C. G. (1955). A preface to history. McGraw-Hill.
Cita Chicago (17th ed.)
Gustavson, Carl Gustav. A Preface to History. New York: McGraw-Hill, 1955.
Cita MLA (9th ed.)
Gustavson, Carl Gustav. A Preface to History. McGraw-Hill, 1955.
Atenció: Aquestes cites poden no estar 100% correctes.