Singhal, R. M., and S. D. Sharma. “Infra-Red Spectroscopy of the Soil Humic Acids of the Sal (<I>Shorea robusta< I>) Forests of Doon Valley”. Indian Forester, vol. 105, no. 9, Sept. 1979, pp. 658-63, doi:10.36808/if/1979/v105i9/11359.