Não informado. (1972). Alternative sources of energy. Alternative Sources of Energy.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रNão informado. Alternative Sources of Energy. Milaca, Minn: Alternative Sources of Energy, 1972.
एमएलए (8वां संस्करण) प्रशस्ति पत्रNão informado. Alternative Sources of Energy. Alternative Sources of Energy, 1972.
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