Biblio

G. A. Best, Bogacka, T., and Niemirycz, E., “International river water quality : pollution and restoration”. E & FN Spon, London, UK, p. xvi, 310 p. : fig., tab., 1997.

D. E. Leland and Damewood, M., “Slow sand filtration in small systems in Oregon”, Journal American Water Works Association, pp. p. 50-59: fig., photogr., tab., 1990.