Merriam Webster's Geographical Dictionary, 3rd ed.:
Neusiedler Lake or Hung. Fertőtó or Ger. Neusiedler See. Shallow lake, E Austria and NW Hungary; 123 sq. mi (319 sq. km.); 23 mi. (37 km.) long; formerly entirely within Hungary, but in 1922 N two thrids transferred with Burgenland to Austria.
Encyclopedia Britannica:
Neusiedler Lake
German NEUSIEDLERSEE, Hungarian FERTO-TÓ, lake in Burgenland (eastern Austria) and northwestern Hungary, named from the Austrian town of Neusiedl and the Hungarian word for "swamp lake." [...]
http://www.bartleby.com/65/ne/Neusiedl.htmlThe Columbia Encyclopedia, Sixth Edition. 2001-05.
Neusiedler Lake
Ger. Neusiedlersee, Hung. Fertö tó, c.130 sq mi (340 sq km), on the Austria-Hungary border SE of Vienna. The lake’s area and depth (average 5 ft/1.5 m) vary considerably with the seasons. [...]