@inproceedings{  
   author = {S. Javanmardi, Y. Ganjisaffar, C. Lopes, P. Baldi},
   title = {An Empirical Analysis of User Contributions in Wikipedia.},
   booktitle = {WikiSym},
   editor = {},
   series = {},
   address = {},
   publisher = {},
   volume = {},   
   pages = {},
   note = {},
   abstract = {},
   keywords = {},
   year = {2009}
}