Liber Extra
Bernard found ample scope for his literary activity in his chosen branch, canon law. From glosses, summaries, and similar works, which had appeared on the "Decretals of Gregory IX" and other collections, he completed, just before his death, a work on the Gregorian Decretals. This, owing to his exact knowledge of former collections and thorough grasp of his subject, won for him the admiration of his contemporaries; so that he was styled "Glossator", and his work, commonly known as "Glossa Ordinaria", became the fruitful source of later glosses, which were printed with Gregory's collection.