Não informado. (1961). Petroleum Abstracts. University of Tulsa, Information Services Division.
Lua i Stíl Chicago (17ú heag.)Não informado. Petroleum Abstracts. Tulsa, Okla: University of Tulsa, Information Services Division, 1961.
Lua MLA (8ú heag.)Não informado. Petroleum Abstracts. University of Tulsa, Information Services Division, 1961.
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