Sommerville, I., & Sawyer, P. (1977). Requirements engineering: A good practice guide. Wiley.
Lua i Stíl Chicago (17ú heag.)Sommerville, Ian, agus Pete Sawyer. Requirements Engineering: A Good Practice Guide. Chichester, Eng. ; New York ; New Delhi: Wiley, 1977.
Lua MLA (8ú heag.)Sommerville, Ian, agus Pete Sawyer. Requirements Engineering: A Good Practice Guide. Wiley, 1977.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.