. http://people.ece.umn.edu/users/riaz/animations/listanimations.html
http://people.ece.umn.edu/users/riaz/animations/sqmoviemotgen.html
http://people.ece.umn.edu/users/riaz/animations/imphasors.html
http://mhhe.com/engcs/electrical/chapman/fundamentals/ind_motor.pdf