J. Conant,
«Assainissement et proprete pour un environnement sain». Hesperian Foundation, Berkeley, CA, USA, p. 48 p. : fig., 2005.
J. Conant,
«Saneamiento y limpieza para un ambiente sano». Hesperian Foundation, Berkeley, CA, USA, p. 48 p. : fig., 2005.
J. Conant,
«Sanitation and cleanliness for a healthy environment». Hesperian Foundation, Berkeley, CA, USA, p. 48 p. : fig., 2005.
