1. Brammerts, H. (1997). Language learning in tandem bibliography [on-line document]. Available: http://www.marvin.unitrier.de/Tandem/learning/tanbib.html
2. Bubenheimer, F. (1997). E-Mail-Projekte im Daβ Unterricht [E-mail projects in teaching German as a foreign language]. [On-line document]. Available: http://www.uni-bielefeld.de/~felixbub/emdafkom.html
3. Pedagogic grammars123145