Cummings, C. (1991). Eco-spirituality: Toward a reverent life. Paulist Press.
Citazione stile Chigago Style (17a edizione)Cummings, Charles. Eco-spirituality: Toward a Reverent Life. Mahwah, New Jersey: Paulist Press, 1991.
Citatione MLA (9a ed.)Cummings, Charles. Eco-spirituality: Toward a Reverent Life. Paulist Press, 1991.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.