Q source
Mark, written around 70 AD, provided the narrative outline for Luke, but Mark contains comparatively little of Jesus' teachings, and for these Luke likely turned to a collection of sayings called Q source, which would have consisted mostly, although not exclusively, of "sayings". Mark and Q account for about 64% of Luke; the remaining material, known as the L source, is of unknown origin and date. Most Q and L-source material is grouped in two clusters, Luke 6:17–8:3 and 9:51–18:14, and L-source material forms the first two sections of the gospel (the preface and infancy and childhood narratives).