dd the folder "conf" to the classpath (Right-click on the project, select "properties" then "Java Build Path" tab (left menu) and then the "Libraries" tab. Click "Add Class Folder..." button, and select "conf" from the list)
D. Metzler, Y. Bernstein, W. Croft, A. Moffat, and J. Zobel. CIKM '05: Proceedings of the 14th ACM international conference on Information and knowledge management, page 517--524. New York, NY, USA, ACM, (2005)
H. Khan, K. Maly, and M. Zubair. Research and Advanced Technology for Digital Libraries, volume 3652 of Lecture Notes in Computer Science, Springer, Berlin / Heidelberg, (2005)