“Leon J. Waszak, Agreement in Principle. The Wartime Partnership of General Władysław Sikorski and Winston Churchill”. Zeitschrift für Ostmitteleuropa-Forschung 48, no. 1 (January 22, 1999): 130–131. Accessed September 16, 2026. https://openjournals.osmikon.de/zfo/article/view/6856.