APA

Velsen J. v., Gierman R. H., World Petroleum Congress (17th. : 2002 sept. 1-5 : Río de Janeiro B. & Gierman R. H.Petrochemical steam crackers as refinery upgrading units. : .

Chicago

Velsen J.F von, Gierman Rik H, World Petroleum Congress (17th. : 2002 sept. 1-5 : Río de Janeiro Brasil) and Gierman Rik H.Petrochemical steam crackers as refinery upgrading units. : .

Harvard

Velsen J. v., Gierman R. H., World Petroleum Congress (17th. : 2002 sept. 1-5 : Río de Janeiro B. and Gierman R. H.Petrochemical steam crackers as refinery upgrading units. : .

MLA

Velsen J.F von, Gierman Rik H, World Petroleum Congress (17th. : 2002 sept. 1-5 : Río de Janeiro Brasil) and Gierman Rik H.: . .