Phelps, E. B., & Velz, C. J. (1950). Public health engineering: A textbook of the principles of environmental sanitation. New York : London: Wiley Chapman & Hall.
Παραπομπή Chicago StylePhelps, Earle B., and Clarence J. Velz. Public Health Engineering: A Textbook of the Principles of Environmental Sanitation. New York : London: Wiley Chapman & Hall, 1950.
Παραπομπή MLAPhelps, Earle B., and Clarence J. Velz. Public Health Engineering: A Textbook of the Principles of Environmental Sanitation. New York : London: Wiley Chapman & Hall, 1950.
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