Allegro Film Productions,

Cerebellum Corporation,

Encyclopaedia Britannica Educational Corp.,

BBC-Discovery Channel Co-production,

KBYU Television,

U.S. Dept. of the Interior, Bureau of Land Management : Utah Oil Gas and Mining : Colorado Division of Minerals & Geology,

BBC ; KRMA Television,

Scott Resources, Inc.,

Discovery Channel Video

University of Wyoming,

Bullfrog Films,