APA (7th ed.) Citation

Ritchie, C. (1997). Operating systems (3rd ed.). Letts Educational.

Chicago Style (17th ed.) Citation

Ritchie, C. Operating Systems. 3rd ed. London: Letts Educational, 1997.

MLA (9th ed.) Citation

Ritchie, C. Operating Systems. 3rd ed. Letts Educational, 1997.