Monier Monier-Williams (1876). Indian Wisdom Or Examples of the Religious, Philosophical and Ethical Doctrines of the Hindus. quote: "Pāṇini himself mentions several grammarians as having preceded him, such as Apisali, Kasyapa, Gargya, Galava, Cakravarmana, Bharadvaja, Sakatayana, Sakalya, Senaka, and Sphoṭayāna. The Unadi-sutras are thought by some to be anterior to Pāṇini." Also discusses the differences in opinions on interpreting Vedic texts, as given by Aurnabhava, Aupamanyava, Agrayana, Katthakya, Kautsa and Shakapuni – all mentioned as "anterior to Yāska" on p. 169