tai lieu 51arch 2014 08
Servo magazine 07 2007
Servo magazine 07 2008
Forbes USA 3-March 2014 (e-magazine full)
Forbes USA 10 February 2014 (e-magazine full)
Forbes USA 20 January 2014 (e-magazine full)
science magazine 2008-07-18
science magazine 2008-07-25
Servo Magazine 07 2006
home power magazine - issue 011 - 1989 - 06 - 07
home power magazine - issue 017 - 1990 - 06 - 07
home power magazine - issue 023 - 1991 - 06 - 07