Podogrodzka, Małgorzata. “Spatial Convergence of the Index of the Old Age in Poland”. Acta Universitatis Lodziensis. Folia Oeconomica 4, no. 324 (February 15, 2017): [51]–65. Accessed May 8, 2024. https://czasopisma.uni.lodz.pl/foe/article/view/553.