Q source
It divides the history of first-century Christianity into three stages, with the gospel making up the first two of these – the arrival among men of Jesus the Messiah, from his birth to the beginning of his earthly mission in the meeting with John the Baptist followed by his earthly ministry, Passion, death, and resurrection (concluding the gospel story "per se"). The gospel's sources are thought to be the Gospel of Mark (for the narrative of Christ's earthly life), the hypothetical sayings collection called the Q source (for his teachings), and a collection of material called the L (for Luke) source, which is found only in this gospel.