Classical Gaelic & Early Modern Irish
www.celtic-languages.org/Classical_Gaelic/Resources - Classical Gaelic resources, books, etc.
www.celtic-languages.org/Notes_on_Classical_Gaelic_Grammar - Notes on Classical Gaelic grammar.
léamh.org - Early Modern Irish texts, glossary, grammar, and paleography.
omniglot.com/language/numbers/celtic3.htm - Numbers 1-10 in Primitive Irish, Old Irish, and Classical Gaelic.