Cita APA (7a ed.)

Perihelion Software Ltd. (1989). The helios operating system (1a ed.). Prentice-Hall International.

Cita Chicago Style (17a ed.)

Perihelion Software Ltd. The Helios Operating System. 1a ed. New York: Prentice-Hall International, 1989.

Cita MLA (9a ed.)

Perihelion Software Ltd. The Helios Operating System. 1a ed. Prentice-Hall International, 1989.