QuotationFinder - Searching for Quotations and Allusions in Greek and   Latin Texts and Establishing the Degree to Which a Quotation or Allusion   Matches Its Source
  The software programs generally used with the TLG (Thesaurus Linguae Graecae) and the CLCLT (CETEDOC Library of Christian Latin Texts) CD-ROMs are not well suited for finding quotations and allusions. QuotationFinder uses more sophisticated criteria as it ranks search results based on how closely they match the source text, listing search results with literal quotations first and loose verbal parallels last. 
Luc Herren
cs.CL