Não informado. (2009). Gas International. Institution of Gas Engineers and Managers.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रNão informado. Gas International. Loughborough, Inglaterra: Institution of Gas Engineers and Managers, 2009.
एमएलए (8वां संस्करण) प्रशस्ति पत्रNão informado. Gas International. Institution of Gas Engineers and Managers, 2009.
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