Singhal, R. M., and S. D. Sharma. 1979. “Infra-Red Spectroscopy of the Soil Humic Acids of the Sal (<I>Shorea robusta< I>) Forests of Doon Valley”. Indian Forester 105 (9):658-63. https://doi.org/10.36808/if/1979/v105i9/11359.