Organisation for Economic Co-operation and Development (OECD)

Waterloo Centre for Groundwater Research

Organización Mundial de la Salud (OMS)

World Health Organization

Saludalia.com/Eresmas

Consejo de Ministros

The Journal of Infectious Diseases 1994; 169:919922.

Water Research 1996; 8:905-913.

Clinical Infectious Diseases 1998;26:138-140.