Mahmoudian, F., Hamidian, A. H., Khorasani, N., & Haghpanah, P. "Risk assessment of ground water pollution by heavy metals in leachate of acidic sludge from motor oil recycling and linear recommendation)Case study: Garmsar(", Journal of Natural Environment, 66, 4, 2014, 435–443. doi: 10.22059/jne.2014.36629