Now in its fourth edition, this is a compendium of Old Irish grammar with translation exercises. It is a companion volume to ‘Old Irish Workbook’ and ‘Selections from the Old-Irish Glosses’. Osborn Bergin's revised edition features additional sections on the comparisons of adjectives and personal pronouns. With Notes and Vocabulary by John Strachan.
John Strachan (1862-1907) was a Celtic, Greek and Sanskrit linguist. He was Professor at Owens College and the Victoria University of Manchester. He was the editor of Stories From the Táin and author of Old Irish Paradigms.
Old Irish learners start here: this is how you master those pesky paradigms and get started reading Old Irish sentences. Full disclosure though, I still get thrown by forms of do-ic every time.