Kwaśniak, D. Łukasz and Cellmer, S. 2021. Incorporating Inter-System Bias in Single Point Positioning Based on GPS, Galileo and BeiDou System. Geomatics and Environmental Engineering. 15, 1 (Feb. 2021), 97–109. DOI:https://doi.org/10.7494/geom.2021.15.1.97.