Leon J. Waszak, Agreement in Principle. The Wartime Partnership of General Władysław Sikorski and Winston Churchill. Zeitschrift für Ostmitteleuropa-Forschung, Marburg, v. 48, n. 1, p. 130–131, 1999. DOI: 10.25627/19994816856. Disponível em: https://openjournals.osmikon.de/zfo/article/view/6856. Acesso em: 31 oct. 2026.