Blaisdell, Donald C. <br/><br/>
Unofficial government :  pressure groups and lobbies. 

 - Philadelphia :  American Academy of Political and Social Science,  1958. 
 - 228 p. 
<br/><br/> The annals of american academy of political and social science. Vol. 319. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>GRUPOS DE PRESION