Bhargava, O. N., and U. K. Bassi. “Trace Fossils from the Palaeozoic-Mesozoic Sequence of Spiti-Kinnaur (Himachal Himalaya) With Comments on Palaeoenvironmental Control on Their Frequency”. Journal of Geological Society of India, vol. 32, no. 3, Sept. 1988, pp. 227-38, https://geosocindia.com/index.php/jgsi/article/view/66224.