Dołzbłasz, Sylwia, and Andrzej Raczyk. “The Role of the Integrating Factor in the Shaping of Transborder Co-Operation: The Case of Poland”. Quaestiones Geographicae, vol. 29, no. 4, Dec. 2010, pp. 65-73, doi:10.2478/v10117-010-0032-3.