Marco Scarpa Antonio Puliafito Massimo Villari Angelo Zaia A Modeling Technique for the Performance Analysis of Web Searching Applications. 1339-1356 2004 16 IEEE Trans. Knowl. Data Eng. 11 http://doi.ieeecomputersociety.org/10.1109/TKDE.2004.65 db/journals/tkde/tkde16.html#ScarpaPVZ04