Não informado. (1976). Erda energy research abstracts. Energy Research and Development Administration.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रNão informado. Erda Energy Research Abstracts. Washington: Energy Research and Development Administration, 1976.
एमएलए (8वां संस्करण) प्रशस्ति पत्रNão informado. Erda Energy Research Abstracts. Energy Research and Development Administration, 1976.
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