Postings here occasionally note Aquinas’s use of Gratian (see here and here). Recently while tracking down some items in the Decretum I was surprised to find a wealth of online Gratian-related canon law resources. The 1582 Editio Romana of Gratian’s Decretum and the Glossa ordinaria are available in a wonderful format at UCLA’s digital canon law collection. (N.B.: the Glossa ordinaria on Gratian should not be confused with the 12^th century commentary on the Latin vulgate with the same name). Emil Friedberg’s edition of Gratian’s work can be found in a variety of formats (e.g., 1, 2, 3). There are also assorted 19^th-century editions of the Decretists on Gratian’s Decretum (e.g., Paucapalea, Rolandus, Rufinus, Stephen of Tournai) on various sites.

What other treasures have I missed?