http://www.anaheimautomation.com/marketing/estun/servo-motors.php?gclid=CjgKEAjwnfGbBRDlxoHrl6uikyESJAD-nzCF1vG8nfqoWcAtw09erG-DtE5H6o0X5E5Y-gf9dTJkCfD_BwE
http://www.automationdirect.com/adc/Overview/Catalog/Motion_Control/Stepper_Systems
http://industrialmotorresource.com/category/variable-speed-motors.html