Biblio

N. L. Calorama - Elburg, «Hand drilled wells», vol. no. 3. Calorama Rural Development Service, Elburg, The Netherlands, p. 65 p. : fig., photogr., tab., tech. drwngs., 1997.

N. L. Calorama - Elburg, «Handpumps», vol. no. 4. Calorama Rural Development Service, Elburg, The Netherlands, p. 59 p.: fig., 1995.

N. L. Calorama - Elburg, «Information on the construction of "low cost" rural water supplies». Calorama Rural Development Service, Elburg, The Netherlands, p. 24 p.: ill., 1994.