SP 500 addition and deletions

I am looking for historical data on additions/deletions for the SP500, I have done some snooping around but not found anything. Does anyone know where this can be found?

Thanks in advance!!

 

wikipedia?

http://en.wikipedia.org/wiki/List_o...t_changes_to_the_list_of_S.26P_500_Components

 

Thanks elite, a good start (not sure why I didn't think to check there).

Have questions about how accurate it is though, and records pre 2009 seem to be a little spotty. Again, a good starting point for me though, thank you!!