McMahon, Glenda Chatterton, Ken Slow sand filter with flow control Slow sand filter with flow control WEDC;Filters and filtration;Technical;Diagram;International and Development Communication 2019-05-08
    https://repository.lboro.ac.uk/articles/figure/Slow_sand_filter_with_flow_control/7908458
10.17028/rd.lboro.7908458.v1