Renewable energy sources in the Region of Warmia and Mazury in north-eastern PolandJanusz Piechocki, Maciej Neugebauer, Joanna Hałacz, Aneta Skotnicka-Siepsiak and Andrzej LangeE3S Web Conf., 154 (2020) 07002DOI: https://doi.org/10.1051/e3sconf/202015407002