TY  - BOOK
AU  - HERBERT ,T.E.
TI  - TELEGRAPHY 
U1  - PE120 
PY  - 1926///
CY  - LONDON 
PB  - SIR ISAAC PITMAN AND SONS LTD 
N1  - PE mean Physics, Electricity and Magnetism Page 450-456 in A to Z Register (Acc. No. Pe1-Pe205)
ER  -