APA

INDEPENDENT ENERGY, . (1989). THE 1990 INDUSTRY DIRECTORY. : .

Chicago

INDEPENDENT ENERGY, . 1989. THE 1990 INDUSTRY DIRECTORY. : .

Harvard

INDEPENDENT ENERGY, . (1989). THE 1990 INDUSTRY DIRECTORY. : .

MLA

INDEPENDENT ENERGY, . THE 1990 INDUSTRY DIRECTORY. : . 1989.