Attribution for quiz data sources.
German word frequency list
Source: http://wortschatz.uni-leipzig.de/Papers/top10000de.txt
License: http://wortschatz.uni-leipzig.de/html/faq/nutzung.html
Author: University of Leipzig. Institut für Informatik, Projekt Deutscher Wortschatz.
Spanish word frequency list
Source: http://en.wiktionary.org/wiki/User:Matthias_Buchmeier/Spanish_frequency_list-1-5000
Source: http://en.wiktionary.org/wiki/User:Matthias_Buchmeier/Spanish_frequency_list-5001-10000
License: http://creativecommons.org/licenses/by-sa/3.0/
Author: Matthias Buchmeier