Ajdukiewicz, Kazimierz. “Two Letters from Kazimierz Ajdukiewicz to Roman Witold Ingarden from 1928”. Ruch Filozoficzny 76, no. 1 (June 1, 2020): 85–89. Accessed July 4, 2025. https://apcz.umk.pl/RF/article/view/RF.2020.007.