Liber Extra
Pierre Mathieu (Petrus Matthæus), a canonist of the sixteenth century, published in 1690, under the title of "Septimus Liber Decretalium" ('Seventh Book of Decretals'), a collection of canons arranged according to the order of the papal Decretals of Gregory IX, containing some Decretals of preceding popes, especially of those from the reign of Sixtus IV (1464–71) to that of Sixtus V, in 1590. It was an entirely private collection and devoid of scientific value. Some editions of the "Corpus Juris Canonici" (Frankfort, 1590; Lyons 1621 and 1671; Justus Henning Boehmer's edition, Halle, 1747) contained the text of this "Liber septimus" as an appendix.