Bharadwaj, D. “On Porostrobus Zeilleri Nathorst and Its Spores With Remarks on the Systematic Position of P. Bennholdi Bode and the Phylogeny of Densosporites Berry”. Journal of Palaeosciences, vol. 7, no. (1-2), Dec. 1958, pp. 67-75, doi:10.54991/jop.1958.571.