Forster, Arnold. <br/><br/>
Violence on the fanatical left and right. 

 - Philadelphia-US :   The american academy of political and social science,   1966. 
 - páginas 141-148 :   ilustraciones blanco y negro 
 - Irregular 
 - Vol. 364 (1966) 
 - The annals of the American academy of political and social science ;    .
 - The american academy of political and social science. .