Artigas (1999); Koertge (i Parusniková & Cohen, 2009, s. 323–338) M. Artigas (1999). The Ethical Nature of Karl Popper's Theory of Knowledge. Bern: Lang. Z. Parusniková og R.S. Cohen, red. (2009). Rethinking Popper. New York: Springer. doi:10.1007/978-1-4020-9338-8.