Gareth J. F. Jones J. T. Foote Karen Sparck Jones S. J. Young Retrieving Spoken Documents by Combining Multiple Index Sources. 30-38 1996 SIGIR db/conf/sigir/sigir96.html#JonesFJY96 conf/sigir/96 SIGIR1996/P030.pdf db/conf/sigir/JonesFJY96.html