Tóth, Žigmund, Helena Frančáková, Miriam Solgajová, and Å tefan Dráb. 2013. “WATER HARDNESS AS AN IMPORTANT PARAMETER OF PH”. Journal of Microbiology, Biotechnology and Food Sciences 2 (special issue 1):2043-51. https://office2.jmbfs.org/index.php/JMBFS/article/view/7301.