DG quotients of DG categories
  Keller introduced a notion of quotient of a differential graded category modulo a full differential graded subcategory which agrees with Verdier's notion of quotient of a triangulated category modulo a triangulated subcategory. This work is an attempt to further develop his theory.   More than a half of the text is devoted to an overview of "well known" definitions and results. As a result, the e-print is essentially self-contained. 
Vladimir Drinfeld