It appears that at the time the fragment was written, both Shepherd of Hermas and Wisdom of Solomon were used in the churches but not admitted to Canon. The letters by Paul to Laodicea and Alexandria are mentioned elsewhere but lost. There is a letter to Laodicea purporting to be from Paul in existence; but its authenticity is challenged. The epistles of John, Jude, and Peter were not generally accepted until the mid second or early third century; but they were used in many churches.
The apocalypse of Peter was not accepted into canon by the councils because of questionable authenticity. It was used by many churches and may be helpful whether canon or not. I know it exists both in Greek and in English; but I have not been able to find it. It is not generally included in the Apocrypha. Many Pseudepigrapha are available online; but I have not found the Apocalypse of Peter.