Prods Oktor Skjærvø, the Agha Khan Professor of Iranian Studies at Harvard University, has published online an impressive series of courses and grammars on ancient Iran (and Central Asia), from the Avestan period to the Middle Ages. The latter encompass basic introductions (including English translations of selected primary sources) to Zoroastrianism and Manichaeism, which I had the pleasure of taking as an undergraduate. The former are grammars of Old and Young Avestan, Old Persian, and Manichaean Sogdian; his Pahlavi grammar is available for download at rabbinics.org. For the most part, these languages lack introductory and/or reference grammars in English, or any language. Skjærvø’s e-grammars are thus fundamental (and open access!) tools for studying the majority of Zoroastrian and Iranian Manichaean texts in their original languages.