The Aṣṭādhyāyī is the central part of Pāṇini's grammar, and by far the most complex. The Ashtadhyayi is the oldest surviving complete linguistic and grammar text of Sanskrit, and Pāṇini refers to previous texts and authors such as the Unadisutra, Dhatupatha, and Ganapatha some of which have not survived. It complements the Vedic ancillary sciences such as the Niruktas, Nighantus, and Shiksha.[49] Regarded as extremely compact without sacrificing completeness, it would become the model for later specialist technical texts or sutras