asalaam alaikum
This is a christian or hebrew dictionary;
http://i256.photobucket.com/albums/hh162/speed2kx/AllahinOT.jpg
http://img294.imageshack.us/img294/2280/allahinot.jpg
Ellah is the hebrew word for God, and the Aramaic equivalent of it is Eloah, and since Arabic is a sister language of them two languages - Allah is the word for God in that language.
The word Ellah is used in the book of Ezra 4:24, and 7:26. These are Jewish, and even Christian sources.