Schwinger-Dyson Equations of Matrix Models for Open and Closed Strings
  We study the Schwinger-Dyson equations of a matrix model for an open-closed string theory. The free energy with source terms for scaling operators satisfies the same Virasoro conditions as those of the pure closed string and is obtained from that of the pure closed string by giving appropriate nonvanishing background values to all of the sources. 
Yukihisa Itoh and Yoshiaki Tanii