The tradition of such guhya or secretive Bhairava is an oral custom that is continuing inside the guru disciple tradition. Their karmakand rituals and tactics are key, they don't seem to be penned down but only learnt and practiced in guru disciple tradition. From the Kala Bhairav Ashtakam by Adi https://vashikaran64186.amoblog.com/the-greatest-guide-to-bhairav-51782991