Não informado. (1980). Environmental Technology Letters. Science and Technology Letters.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रNão informado. Environmental Technology Letters. London: Science and Technology Letters, 1980.
एमएलए (8वां संस्करण) प्रशस्ति पत्रNão informado. Environmental Technology Letters. Science and Technology Letters, 1980.
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