ELSON, B. and SHAW, R.
(1999):
Simple drilling methods-Brief 43.
En: SHOW, R. (editor). Running Water, More Technical Briefs on Health, Water and Sanitation.
Nottingham (UK):
Water, Engineering and Development Centre (WEDC)/ Intermediate Technology (IT) Publications, pp.41-44.
URL
[Accessed: 29.08.2018]
PDF
