کتاب های Richard Helmer
درباره نویسنده
![](https://upload.wikimedia.org/wikipedia/commons/thumb/6/60/Richard_M_Helms.jpg/36px-Richard_M_Helms.jpg)
![Water pollution control: a guide to the use of water quality management principles](http://cdn.ketabkoo.com/covers/0/30333-n.jpg)
Water pollution control: a guide to the use of water quality management principles
Richard Helmer,Ivanildo Hespanhol,United Nations Environment Programme.,Water Supply and Sanitation Collaborative Council.,World Health Organization., 1997![Water Pollution Control: A Guide to the Use of Water Quality Management Principles](http://cdn.ketabkoo.com/covers/0/30334-n.jpg)
Water Pollution Control: A Guide to the Use of Water Quality Management Principles
Richard Helmer, Ivanildo Hespanhol, 1998![Water Pollution Control: A Guide to the Use of Water Quality Management Principles](http://cdn.ketabkoo.com/covers/2/290133-n.jpg)
Water Pollution Control: A Guide to the Use of Water Quality Management Principles
Richard Helmer, 1997![Water Pollution Control: A Guide to the Use of Water Quality Management Principles](http://cdn.ketabkoo.com/covers/3/349772-n.jpg)