A useful table from the "Grammatik des Pali" by Achim Fachs which allows to find the Ancient Indian correspondences of the Pali words.
Jain sacred books, composed in Ardha-Magadhi language, a close relative of Pali.
An article by Dr Devendra Kumar Jain about the history of Indian languages, including Pali.
Introduction to the more important language families including Indo-European, Uralic, Altaic, Afro-Asiatic, Sino-Tibetan, Malayo-Polynesian, Niger-Congo, Dravidian and others.
Chapter from the book "The Development of Hinduism" by Prof. M.M. Ninan.