Paul Guinness; Brenda Walpole. (2012). Environmental Systems and Societies for the IB Diploma. CAMBRIDGE UNIVERSITY PRESS.
Lua i Stíl Chicago (17ú heag.)Paul Guinness; Brenda Walpole. Environmental Systems and Societies for the IB Diploma. CAMBRIDGE UNIVERSITY PRESS, 2012.
Lua MLA (9ú heag.)Paul Guinness; Brenda Walpole. Environmental Systems and Societies for the IB Diploma. CAMBRIDGE UNIVERSITY PRESS, 2012.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.