Follett. (1980). Triple. Signet Book Penguin Group.
Cita Chicago (17th ed.)Follett. Triple. NewYork,USA: Signet Book Penguin Group, 1980.
Cita MLA (9th ed.)Follett. Triple. Signet Book Penguin Group, 1980.
Atenció: Aquestes cites poden no estar 100% correctes.