Jerzy Bobryk
(2009). The genesis and history of Twardowski's theory of actions and products. In S. Lapointe, J. Woleński, M. Marion, & W. Miskiewicz (Eds.). The Golden age of Polish philosophy (pp. 33-42). Dordrecht: Springer.
(2008). Epistemology after Wittgenstein or a general theory of action. Dialogue and universalism, 18 (1-3), 149-156. https://doi.org/10.5840/du2008181/3109.