PIEKUT, Marlena. Comparison of R&D Expenditures in Selected Countries. Comparative Economic Research. Central and Eastern Europe, [S. l.], v. 16, n. 3, p. 107–126, 2013. DOI: 10.2478/cer-2013-0021. Disponível em: https://www.czasopisma.uni.lodz.pl/CER/article/view/6891. Acesso em: 15 feb. 2026.