APA

United States, . (1989). Survey of government assistance for the world's hard coal industries. [Washington, D.C.?]: U.S. Dept. of Commerce, International Trade Administration, Office of Energy.

Chicago

United States, . 1989. Survey of government assistance for the world's hard coal industries. [Washington, D.C.?]: U.S. Dept. of Commerce, International Trade Administration, Office of Energy.

Harvard

United States, . (1989). Survey of government assistance for the world's hard coal industries. [Washington, D.C.?]: U.S. Dept. of Commerce, International Trade Administration, Office of Energy.

MLA

United States, . Survey of government assistance for the world's hard coal industries. [Washington, D.C.?]: U.S. Dept. of Commerce, International Trade Administration, Office of Energy. 1989.