Karpińska, M. 2026. The Story of a Turbulent Friendship. Karol Sienkiewicz and Piotr Kopczyński: Schoolmates at the Krzemieniec Lyceum: Friends – Neighbours – Political Opponents. Relacje – więzi – parantele. J. Kita and M. Korybut-Marciniak, eds. Lodz University Press. 295–308.