Παραπομπή APA

Covington, G. (2010). International encyclopedia of sustainable development. Apple academic.

Παραπομπή Chicago Style

Covington, Gareth. International Encyclopedia of Sustainable Development. Oakville: Apple academic, 2010.

Παραπομπή MLA

Covington, Gareth. International Encyclopedia of Sustainable Development. Apple academic, 2010.