Berck, P., & Helfand, G. E. (2011). The economics of the environment. PHI Learning.
Chicago-čujuhus (17. p.)Berck, Peter, juo Gloria E. Helfand. The Economics of the Environment. New Delhi: PHI Learning, 2011.
MLA-čujuhus (9. p.)Berck, Peter, juo Gloria E. Helfand. The Economics of the Environment. PHI Learning, 2011.
Muitte dárkkistit čujuhemiid riektatvuođa, ovdal go geavahat daid iežat deavsttas.