1. Water quality in three typical rivers in U.P. — Ganga, Yamuna and Kali;Bhargava,1977
2. A water quality index—Do we dare?;Brown;Water and Sewage Works,1970
3. An objective water quality index;Harkins;J. Wat. Pollut. Control Fed.,1974
4. An index number system for rating water quality;Horton;J. Wat. Pollut. Control. Fed.,1965