Dyfyniad APA

National Geographic Society (Washington, D.C.), WQED (Television station : Pittsburg, Pa.), & Seamans, J. (1991). Great lakes, fragile seas [videorecording]. The Society.

Dyfyniad Arddull Chicago

National Geographic Society (Washington, D.C.), Pa.) WQED (Television station : Pittsburg, and Joe Seamans. Great Lakes, Fragile Seas [videorecording]. Washington, D.C: The Society, 1991.

Dyfyniad MLA

National Geographic Society (Washington, D.C.), et al. Great Lakes, Fragile Seas [videorecording]. The Society, 1991.

Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.