THE HELIOS OPERATING.. (1989). The helios operating system: Perihelion software ltd. Prentice Hall.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रTHE HELIOS OPERATING.. The Helios Operating System: Perihelion Software Ltd. New York: Prentice Hall, 1989.
एमएलए (9वां संस्करण) प्रशस्ति पत्रTHE HELIOS OPERATING.. The Helios Operating System: Perihelion Software Ltd. Prentice Hall, 1989.
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