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		| Paper: | 
		Martin Schwarzschild's Contributions to Galaxy Dynamics | 
	 
	
		| Volume: | 
		182, Galaxy Dynamics: A Rutgers Symposium | 
	 
	
		| Page: | 
		3 | 
	 
	
		| Authors: | 
		Merritt, David | 
	 
	
	
		| Abstract: | 
		Nuclear disks of neutral and ionized gas are common in early-type galaxies. We review their morphological and kinematical characteristics. In many cases they show near-Keplerian rotation curves which allow good estimates of the central black hole masses. They also present a number of puzzles with respect to their origin and stability. | 
	 
	
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