Não informado. (1969). Environmental Health. Environmental Health Officers Association.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रNão informado. Environmental Health. London: Environmental Health Officers Association, 1969.
एमएलए (8वां संस्करण) प्रशस्ति पत्रNão informado. Environmental Health. Environmental Health Officers Association, 1969.
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