HAGEL JOHN. (2005). ONLY SUSTAINABLE EDGE. HARVARD BUSINESS SCHOOL PRESS.
Lua i Stíl Chicago (17ú heag.)HAGEL JOHN. ONLY SUSTAINABLE EDGE. BOSTON: HARVARD BUSINESS SCHOOL PRESS, 2005.
Lua MLA (9ú heag.)HAGEL JOHN. ONLY SUSTAINABLE EDGE. HARVARD BUSINESS SCHOOL PRESS, 2005.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.