McMahon, Glenda Shaw, Rod Water-seal fitted and VIP Water-seal fitted and VIP WEDC;Sanitation ladders;Technical;Diagram;Toilets;Sanitation;International and Development Communication 2019-04-30
    https://repository.lboro.ac.uk/articles/figure/Water-seal_fitted_and_VIP/7982843
10.17028/rd.lboro.7982843.v1