But, unlike the case of the Mahapuranas, the different lists of eighteen Upapuranas seldom agree with one another with regard to the names of these texts.
Unlike the Mahapuranas, most of the Upapuranas have been able to preserve their older materials along with their distinctive sectarian character.
All extant Upapuranas can be broadly divided into six groups according to the sectarian views found in these texts: Vaishnava, Shakta, Shaiva, Saura, Ganapatya and non-sectarian.
The extant Shivadharma Purana comprises 24 chapters and deals only with the religious rites and duties of the worshippers of Shiva.
[1] Dr. R. C. Hazra's magnum opus for which he earned a D. Litt was a detailed catalogue of contents, comparison of manuscripts of Upapuranas; popularly known as Studies in the Upapurāṇas.
It was series of five volumes of equal length, a part of the Calcutta Sanskrit College Research Series (out of which only two were published by Munshiram Manoharlal, both generally edited by Gaurinath Sastri and Hazra's handwritten papers of the other three volumes are kept with the College); on a descriptive study of all more than hundred Upapuranas, which, even to this day, remains an important but ignored field of Sanskrit literature.