Kubiak-Wójcicka, K., Pokropski, T. (2019). 
	Intensity of inland navigation on the lower Vistula river based
	on the analysis of lockage in Włocławek in the years 1997–2016. Geographical Studies, 2019, 79-99. doi: https://doi.org/10.4467/20833113PG.19.004.10308