2011 Norway attacks – Wikipedia

According to the authorities, Brunon Kwiecień was an admirer of Breivik and was further inspired by the Oklahoma City bombing. [339] Poland’s Internal Security Agency (ABW) first found out about Kwiecień after it launched investigation into Breivik’s Polish contacts when it became known that Breivik had ordered some of the chemicals for his bomb from Poland via internet.

: https://en.wikipedia.org/wiki/Brunon_Kwiecie%C5%84