http://www.pbs.org/wgbh/aso/databank/entries/do12we.html http://www.pbs.org/wgbh/aso/databank/entries/do12we.html continental drift http://www.pbs.org/wgbh/aso/databank/entries/do12we.html continental drift Alfred Wegener Alfred Wagner Alman Alfred WEGENER kýtasal kayma kuramýný ortaya attý continental drift Alfred Wagner