Singh, Y. K. (2006). Environmental science. New Age International (P) Ltd., Publishers.
Dyfyniad Arddull ChicagoSingh, Y. K. Environmental Science. New Delhi: New Age International (P) Ltd., Publishers, 2006.
Dyfyniad MLASingh, Y. K. Environmental Science. New Age International (P) Ltd., Publishers, 2006.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.