Cita APA (7th ed.)
(1991). Fred. Ashton-Tate.
Cita Chicago (17th ed.)
Fred. Torrance, Calif.: Ashton-Tate, 1991.
Cita MLA (9th ed.)
Fred. Ashton-Tate, 1991.
Atenció: Aquestes cites poden no estar 100% correctes.