Changes

* ARGOSS (2001). [http://www.susana.org/_resources/documents/default/2-1926-argoss-manual.pdf Guidelines for Assessing the Risk to Groundwater from on-Site Sanitation]. British Geological Survey Commissioned Report, CR/01/142, Keyworth, UK. :Available at: [http://www.bgs.ac.uk bgs.ac.uk]

* Franceys, R., Pickford, J. and Reed, R. (1992). [https://www.susana.org/_resources/documents/default/2-1651-who-a-guide-to-the-development-of-on-site-sanitation.pdf A Guide to the Development of on-Site Sanitation]. WHO, Geneva, CH.:Available at: [http://www.susana.org/library susana.org/library]

* Graham, J. P. and Polizzotto, M. L. (2013). [https://pubmed.ncbi.nlm.nih.gov/23518813/ Pit Latrines and Their Impacts on Groundwater Quality: A Systematic Review]. Environmental Health Perspectives, National Institute of Environmental Health Sciences, Research Triangle Park, US.:Available at: [http://www.ehponline.org ehponline.org]

* Mara, D. D. (1984). [https://www.pseau.org/outils/ouvrages/world_bank_the_design_of_ventilated_lmproved_pit_latrines_1984.pdf The Design of Ventilated Improved Pit Latrines]. UNDP Interregional Project INT/81/047, The World Bank and UNDP, Washington, D.C., US. :Available at: [http://documents.worldbank.org/curated/en/home documents.worldbank.org/curated/en/home] (A good reference for detailed double VIP design information)

* Mara, D. D. (1996). Low-Cost Urban Sanitation. Wiley, Chichester, UK. (Book; General description of VIPs with a focus on the ventilation system)

* Morgan, P. R. (2009). [http://www.ecosanres.org/pdf_files/EcologicalToilets-PeterMorgan-Mar2009.pdf Ecological Toilets. Start Simple and Upgrade from Arborloo to VIP]. Stockholm Environment Institute, Stockholm, SE. :Available at: [http://www.ecosanres.org ecosanres.org]