Physicochemical or geochemical

• Webb, E., Stewart, C., Sami, E., Kelsey, S., Fairbairn Dunlop, P., Dennison, E., (2021), Variability of naturally occurring fluoride in diverse community drinking-water sources, Tanna Island, Vanuatu, Journal of Water, Sanitation & Hygiene for Development, 11(4), 591-599, 10.2166/washdev.2021.270