The field of biblical studies that seeks to “establish the literary sources the biblical author/editor drew upon.”1

• From 40 Questions About Interpreting the Bible by Robert Plummer, page 300:

Source criticism seeks to establish the literary sources the biblical author/editor drew upon. For example, Julius Wellhausen (1844-1918), a liberal Old Testament scholar, argued that the Pentateuch was composed of four literary strands: the Yahwist or Jehovist (J), Elohistic (E), Priestly (P), and Deuteronomistic (D) sources. The evidence for the JEPD construction is actually quite tenuous. The data support traditional Mosaic authorship of the Pentateuch, while obviously allowing for some gathering and editing of the Mosaic material. 

In the New Testament, source criticism is especially applied to Matthew, Mark, and Luke (the Synoptic Gospels) because of their close similarity in wording and order. The majority of New Testament scholars believe that Luke and Matthew used two main sources in their composition—the written gospel of Mark and “Q.” “Q” is an abbreviation for the German word Quelle (source) and stands for a collection of written and oral sources that Matthew and Luke had in common. Indeed, Luke explicitly indicates that he drew upon multiple sources in the composition of his Gospel (Luke 1:1-4). As many early church fathers comment on the literary sources behind the Gospels (i.e., which Gospel author(s) were dependent on others), source criticism is truly an ancient discipline. 

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