`  :The problem is that by itself Wikipedia is not a reliable reference. Rather than try to use Wikipedia articles as refs for Wikipedia articles, which leads to a bootstrapping problem, it is better to go to the other article and then have a look though its refs and see if any are suitable to use in the first article. One thing to be aware of is that because Wikipedia is now ten years old that in some cases unreferenced information taken from it has been used in other articles and websites and then those have been used as refs for the original Wikipedia article, again creating a ``bootstrap`` problem of circular referencing. That way incorrect information can be widely spread and seemingly well referenced.  :As far as Aviation transponder interrogation modes goes, if all the information has been reincorporated back into SSR then I think it should be redirected back into SSR and not left out there. Otherwise we have two articles on the same subject that say different things. I have not checked to see if there are any useful refs in that article that could be transfered back. Perhaps you would be the best judge of that.  :We also need to get much better and more complete referencing for SSR or else editors will slowly start removing tagged text as original research. -   `