Subject: Canon Law
Author of work: Gregorius IX
Title: Decretales
Subject: Sermons
Author of work: Leo I Papa
Title: Sermones
Subject: Canon Law
Author of work: Johannes Andreae
Title: Comment. in Sextum librum Decretalium
Subject: Theology
Author of work: Gregorius I
Title: Moralia
Subject: Biblica
Title: Biblia
Subject: Music
Title: Polyphonic music
Subject: Canon Law
Author of work: Guido de Baysio
Title: Comment. in Sextum librum Decretalium
Subject: Canon Law
Author of work: Gratianus
Title: Decretum
Subject: Civil Law
Author of work: Justinianus
Title: Digestum vetus