Friis, R. H. (2012). Essentials of environmental health (2nd ed.). Jones & Bartlett learning.
Chicago-viite (17. p.)Friis, Robert H. Essentials of Environmental Health. 2nd ed. Burlington: Jones & Bartlett learning, 2012.
MLA-viite (9. p.)Friis, Robert H. Essentials of Environmental Health. 2nd ed. Jones & Bartlett learning, 2012.
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