Feather, R. M., & Snyder, S. L. (1999). Glencoe earth science. Glencoe/McGraw Hill.
Dyfyniad Arddull ChicagoFeather, Ralph M., and Susan Leach Snyder. Glencoe Earth Science. New york: Glencoe/McGraw Hill, 1999.
Dyfyniad MLAFeather, Ralph M., and Susan Leach Snyder. Glencoe Earth Science. Glencoe/McGraw Hill, 1999.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.