Kim Paffenroth 
Story of Jesus According to L [PDF ebook] 

Using stylistic, formal and thematic criteria, Paffenroth reconstructs a pre-Lukan source (L) for much of the unique material in Luke 3-19. This source portrays Jesus primarily as a healer and teller of parables, a portrayal very different from that of the suffering Son of Man in Mark, the aphoristic teacher of Wisdom in Q, or the depiction of Jesus as universal saviour that Luke himself prefers. This source is quite primitive, probably earlier than Mark, perhaps as early as Q, to which it is quite similar in form, if not content.