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		| Paper: | 
		The AGN Content of Hard X-ray Surveys | 
	 
	
		| Volume: | 
		284, AGN Surveys, IAU Colloquium 184 | 
	 
	
		| Page: | 
		235 | 
	 
	
		| Authors: | 
		Comastri, Andrea; Vignali, C.; Brusa, M.; The Hellas; Hellas2XMM Consortia | 
	 
	
	
		| Abstract: | 
		The broad band properties of a large sample of hard X--ray selected sources discovered by BeppoSAX, ASCA, Chandra and XMM surveys are used to discriminate among competing scenarios for the synthesis of the hard X--ray background (XRB) and to evaluate their contribution to the far-infrared and sub-millimeter backgrounds (FIRB). In particular we discuss the role of heavily obscured, Compton thick sources arguing how their properties can be much better constrained through a combined fit of XRB and FIRB spectra. | 
	 
	
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