Sharma, A., Sharma, V. K., Parwar, R., Joshi, N., Prakash, M., Nirmala, M., & Verma, V. (2006). Morphological details of new irregular Echinoid fossil from Zirabad, India. Environment Conservation Journal, 7(3), 107–111. https://doi.org/10.36953/ECJ.2006.070317