@ARTICLE{
       Author = {Dimitropoulos, X. and Serrano, M. and Krioukov, D.}, 
       Title = {{On Cycles in AS Relationships}},
       Journal = {ACM SIGCOMM Computer Communication Review (CCR)}, 
       Volume = {38},
       Number = {3},
       Pages = {102-104},
       Month = {Jul},
       Year = {2008},
       Keywords = {routing   topology}
}