Indian Railway standard specification for polarised relay, 3 - position / 
Govt. of India Ministry of transport, Railways and dept. 
 - Lucknow :  R. D. A. S. O.,  [n. d.] 
 - 23 p. ;  22 cm. 
<br/><br/><label>ISBN: </label> Rs.15.00 
<br/><br/><label>Dewey Class. No.: </label>6256.(54)