Lipschutz, Seymour. <br/><br/>
Schaum's outline of theory and problems of set theory and related topics / 
Seymour Lipschutz. 
 - 2nd ed. 
 - New York :  McGraw-Hill,  c1999. 
 - 282 p. : ill. 
<br/><br/> Includes index. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Aggregates