Supady, Grzegorz. “Not Only the Bible and the Hymnal. On Discovered Books by Gustaw Kayka (1893–1945)”. Bibliotekarz Podlaski 50, no. 1 (May 28, 2021): 203–214. Accessed April 20, 2024. https://bibliotekarzpodlaski.pl/index.php/bp/article/view/585.