Jestem za Unią Europejską, 21 Apr 2015 http://link.springer.com/article/10.1007/s10699-014-9350-6 link.springer.com
Fan Klub Krysztofiaka, 17 Feb 2015 http://link.springer.com/article/10.1007/s10699-014-9350-6 link.springer.com