TY  - BOOK
AU  - Helfand, Lewis
TI  - They changed the world: Edison-Tesla-Bell
SN  - 9789380741871
U1  - 621.3 
PY  - 2019///
CY  - New Delhi
PB  - Kalyani Navyug Media Pvt. Ltd. 
KW  - Inventors
KW  - United States
ER  -