2[3]Chi-Fu Tai,Wen-Yun Su,Chang-Fa Yang,Chi-jui Wu,Shih-Shong Yen.Alarm device designed to warn of danger of hitting high voltage power line by crane in motion[p].US Patent Issued on September 26,2000
3[4]H.Kenneth Sacks,Michael R.Yenchek,Gerald T.Homce,James C.Cawley.Alarm system for detecting hazards due to power transmission lines[p].US Patent Issued on July 29,2003
