Gupta, S., R. Khare, O. Bajpai, H. Rai, D. K. Upreti, R. K. Gupta, and P. K. Sharma. “Lichen As Bioindicator for Monitoring Environmental Status in Western Himalaya, India”. International Journal of Environment, vol. 5, no. 2, May 2016, pp. 1-15, doi:10.3126/ije.v5i2.15001.