Various. The National Geographic Magazine, Vol. I., No. 2, April, 1889.
Dyfyniad Arddull ChicagoVarious. The National Geographic Magazine, Vol. I., No. 2, April, 1889.
Dyfyniad MLAVarious. The National Geographic Magazine, Vol. I., No. 2, April, 1889.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.