  The boundedness of the bilinear fractional integral operator is investigated.
This bilinear fractional integral operator goes back to Kenig and Stein. This
paper is oriented to the boundedness of this operator on products of Morrey
spaces. Compared to the earlier work by He and Yan, the local integrability
condition of the domain is expanded. The local integrability condition can be
relaxed with the help of the averaging technique.
