Olejnik, Alicja, Agata Żółtaszek, and Jakub Olejnik. “Spatial Solution to Measure Regional Efficiency — Introducing Spatial Data Envelopment Analysis”. Economy of Regions 17, no. 4 (December 29, 2021): 1166–1180. Accessed July 13, 2024. https://economyofregions.org/ojs/index.php/er/article/view/82.