1. Lecture Notes in Computer Science;A. Arato,2004
2. Freedom Scientific Inc.: PAC Mate BNS (2004),
http://www.freedomscientific.com/fs_products/PACmate_bns.asp
3. Technologies HumanWare Canada Inc.: Maestro PDA (2005) ,
http://humanware.ca/web/en/p_DA_Maestro.asp
4. log4j project:
http://logging.apache.org/log4j/docs/
5. Hungarian Electronic Library:
http://vmek.oszk.hu/