Ralphs, J. D. <br/><br/>
Principles and practice of multi-frequency telegraphy  [Books]. 
J. D. Ralphs. 
 - London  Peter Peregrinus Ltd.  1985 
 - Pages: 205. 
<br/><br/><label>ISBN: </label>0863410227  0.00 
<br/><br/><label>Subjects--Personal Names: </label><br/>Telegraph , wireless.
<br/><br/><label>Dewey Class. No.: </label>TK/5741  / RAL