Farago, Peter Stephen. <br/><br/>
Free-electron physics / 
P. S. Farago. 
 - Harmondsworth :  Penguin,  1970. 
 - 269 p. :  ill. ;  21 cm. 
 - Penguin library of physical sciences: physics Penguin education .
<br/><br/> Includes index. 
<br/><br/><label>ISBN: </label>0140800999 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Electron optics.<br/>Vacuum-tubes.