One of the places where i know the GOSPEL OF PETER is found, is in the LOST BOOKS OF THE BIBLE AND THE FORGOTTEN BOOKS OF EDEN. This book was originally published BEFORE the discovery of the dead sea scrolls and the Nag Hammadi library. (the Gnostic Scrolls) THe Gospel of Peter was discovered in 1886, and is actually just a fragment. For the most part its an account of the passion, from the night trial before Pilate, until the place where Peter and Andrew go fishing. This Gospel is mentioned by many of the ancient writers, and was presumed lost. I would guess, that just like the "Q" gospel that was used along with Mark, to help write Luke and Matthew, that this Gospel of Peter was used, back in the time when there were no complete gospels, in the sense of the long stories. I guess you had the sayings gospel Thomas and "Q", the account of the crusifixion by Peter, the early form of John, which was a list of the miracles. In my estimation, this Gospel of Peter is very important. However, since i think that for the most part, it was used for the four canonical gospels very closely, it was not nessacary, and like the "Q" gospel, etc, it was either not copied, or was not SUPPOST to be copied. (maybe like the secret gospel of MARK?) The only real difference i found, was that when Jesus was on the cross, he cries out MY POWER MY POWER, instead of MY FATHER MY FATHER. There are many more details in the telling of the passion, which isnt in the canonical gospels. Also, for those who are interested in the way that women were much more important in the early church, Mary Magalene was much more important in this Gospel of Peter. (So, was it part of the goal to mitagate the role of women in the church?) I hope that helps.