APA استشهاد

Duggal, K. (1996). Elements of environmental engineering (6th ed.). S.Chand & Co.

استشهاد بنمط شيكاغو

Duggal, K.N. Elements of Environmental Engineering. 6th ed. New Delhi: S.Chand & Co, 1996.

MLA استشهاد

Duggal, K.N. Elements of Environmental Engineering. 6th ed. S.Chand & Co, 1996.