Beekes Robert. A Grammar of Gatha-Avestan

Leiden: Brill, 1988. — 266 p.This is up-to-date work on the language of the Avestan Gathas (not the later language). The emphasis is on the historical development of the language and its relationship to other Indo-European languages, rather than a guide to reading the texts. However, the astute student should be able to find everything here necessary for understanding the Gathic hymns. Grammar and pronunciation are exhaustively presented, and most of the vocabulary used in the texts is found somewhere in the book.