Płonka, Maria, and Tomasz Jedynak. “A Statistical Analysis of the Relationship Between the Scope and Efficiency of Mutual Insurance Companies in Poland”.
Krakow Review of Economics and Management/Zeszyty Naukowe Uniwersytetu Ekonomicznego w Krakowie, no. 907 (December 20, 2015): 123–136. Accessed July 16, 2025.
https://krem.uek.krakow.pl/index.php/krem/article/view/803.