If you have questions about what form a noun takes in different cases, a good place to find the answer is in the German Wiktionary. It IS all in German, but you will find an easily readable table showing the declension of the noun on the right side of the page for that noun. The starting page is http://de.wiktionary.org/wiki/Wiktionary:Hauptseite . Just enter the word of interest into the search box, and away you go.