TY  - BOOK
AU  - Asthana ,D.K
AU  - Asthana, M
TI  - A textbook of Environmental studies
SN  - 8121927641
AV  - QH541.A8 2006 
PY  - 2006///
CY  - New delhi
PB  - schanda & company
KW  - ecology
ER  -