LERATO LETHEA. Impact of water hardness on energy consumption of geyser heating elements. Water SA, [S. l.], v. 43, n. 4 October, 2017. DOI: 10.4314/wsa.v43i4.09. Disponível em: https://watersa.net/article/view/10598. Acesso em: 6 apr. 2025.