Walęcka-Matyja, Katarzyna Kamila. “Psychological Study of Siblings Subsystems – Methodological Considerations”. Quarterly Journal Fides et Ratio 57, no. 1 (March 28, 2024): 67–75. Accessed August 2, 2025. https://fidesetratio.com.pl/ojs/index.php/FetR/article/view/1253.