The custom of these guhya or secretive Bhairava is an oral tradition that is continuous while in the guru disciple tradition. Their karmakand rituals and practices are top secret, they don't seem to be written down but only learnt and practiced in Expert disciple tradition. From the Kala Bhairav Ashtakam https://keeganddayv.webdesign96.com/30610102/considerations-to-know-about-bhairav