O'Kelly, M., Ryan-Enright, M., Whelan, D., & Geoghegan, A. (1990). Discover our world: Environmental studies; nature, civics, science (Third class.). Folens.
Citazione stile Chigago Style (17a edizione)O'Kelly, Mary, Mary Ryan-Enright, Deirdre Whelan, e Adrienne Geoghegan. Discover Our World: Environmental Studies; Nature, Civics, Science. Third class. Dublin: Folens, 1990.
Citatione MLA (9a ed.)O'Kelly, Mary, et al. Discover Our World: Environmental Studies; Nature, Civics, Science. Third class. Folens, 1990.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.