G. R. S. Mead 
The Hymn of Jesus: Echoes from the Gnosis [EPUB ebook] 

Just as many other settings of the Sayings and Doings of the Lord existed prior to and alongside of the canonical Gospels, so were there, prior to and alongside of the subsequently selected or canonical Acts, many other narratives professing to record the doings and sayings of the Apostles and Disciples of the Lord. Most of these originated in circles which were subsequently called heretical, and many of them were later on worked over by orthodox editors to suit doctrinal preconceptions, and so preserved for the edification of large numbers in the Catholic or General Church.