APA
International Gas Union I., . (1976). Commercial and technical aspects of natural gas contracts. [s.l.]: International Gas Union, IGU.
Chicago
International Gas Union IGU, . 1976. Commercial and technical aspects of natural gas contracts. [s.l.]: International Gas Union, IGU.
Harvard
International Gas Union I., . (1976). Commercial and technical aspects of natural gas contracts. [s.l.]: International Gas Union, IGU.
MLA
International Gas Union IGU, . Commercial and technical aspects of natural gas contracts. [s.l.]: International Gas Union, IGU. 1976.