Doryń W, Wawrzyniak D. Heterogeneity in Air Pollution Levels and Their Techno‑economic Determinants: A Cluster Analysis of the EU–27. CER [Internet]. 2024 Sep. 30 [cited 2025 Dec. 19];27(3):47-66. Available from: https://czasopisma.uni.lodz.pl/CER/article/view/23853