Justinian's Corpus iuris civilis  (Digest, Code, Institutes)

Pepo (1075)
Irnerius
The Four Doctors of Roman Law (Jacobus, Martinus, Bulgarus, and Hugo)
Azo and Accursius (Ordinary Gloss on the Corpus iuris civilis)
 

Canon Law

Sources of Canon Law

Conciliar Canons (local and general)
Papal Decretals (letters)
Church Fathers
Custom

Gratian, Concordia discordantium canonum = Decretum
Huguccio, Johannes Teutonicus (Ordinary Gloss), Innocent IV, Hostiensis

Doctor utriusque iuris