Alexis Sanderson notes that the Vajrayāna Yogini tantras draw extensively from the material also present in Shaiva Bhairava tantras classified as "Vidyapitha". Sanderson's comparison of them shows similarity in "ritual procedures, style of observance, deities, mantras, mandalas, ritual dress, Kapalika accouterments like skull bowls, specialized terminology, secret gestures, and secret jargons. There is even direct borrowing of passages from Shaiva texts." Sanderson gives numerous examples such as the "Guhyasiddhi" of Padmavajra, a work associated with the Guhyasamaja tradition, which prescribes acting as a Shaiva guru and initiating members into Saiva Siddhanta scriptures and mandalas. Sanderson claims that the Samvara tantra texts adopted the pitha list from the Shaiva text "Tantrasadbhava", introducing a copying error where a deity was mistaken for a place.