Friis, R. H. (2012). Essentials of environmental health (2nd ed.). Jones & Bartlett Learning.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रFriis, Robert H. Essentials of Environmental Health. 2nd ed. Sudbury, MA: Jones & Bartlett Learning, 2012.
एमएलए (8वां संस्करण) प्रशस्ति पत्रFriis, Robert H. Essentials of Environmental Health. 2nd ed. Jones & Bartlett Learning, 2012.
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