Kalu, N. (2018). Natural Water, Hardness, Pollution, Water Cycle, Treatment and Uses. Afribary. Retrieved from https://afribary.com/works/natural-water-hardness-pollution-water-cycle-treatment-and-uses-981
Kalu, Nnenna "Natural Water, Hardness, Pollution, Water Cycle, Treatment and Uses" Afribary. Afribary, 29 Jan. 2018, https://afribary.com/works/natural-water-hardness-pollution-water-cycle-treatment-and-uses-981. Accessed 21 Jan. 2025.
Kalu, Nnenna . "Natural Water, Hardness, Pollution, Water Cycle, Treatment and Uses". Afribary, Afribary, 29 Jan. 2018. Web. 21 Jan. 2025. < https://afribary.com/works/natural-water-hardness-pollution-water-cycle-treatment-and-uses-981 >.
Kalu, Nnenna . "Natural Water, Hardness, Pollution, Water Cycle, Treatment and Uses" Afribary (2018). Accessed January 21, 2025. https://afribary.com/works/natural-water-hardness-pollution-water-cycle-treatment-and-uses-981