(1978). Coal: The other energy [kasetvideo]. Washington, D C : National Audio Visual Center.
Chicago-čujuhus (17. p.)Coal: The Other Energy [kasetvideo]. Washington, D C : National Audio Visual Center, 1978.
MLA-čujuhus (9. p.)Coal: The Other Energy [kasetvideo]. Washington, D C : National Audio Visual Center, 1978.
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