Kasprzak, Agata, et al. “Changes in the Chemical Composition of Groundwater in Quaternary Aquifer in Old Krakow, Poland (years 2002-2012)”. Geology, Geophysics and Environment, vol. 39, no. 2, June 2013, p. 143, https://doi.org/10.7494/geol.2013.39.2.143.