Day, W. H. (1966). Petroleum marketing practices and problems. Commercial Pub.
Lua i Stíl Chicago (17ú heag.)Day, William Henry. Petroleum Marketing Practices and Problems. Tulsa, Okla: Commercial Pub, 1966.
Lua MLA (9ú heag.)Day, William Henry. Petroleum Marketing Practices and Problems. Commercial Pub, 1966.
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