Petrich, M <br/><br/>
Lectures in semigroups 
M. Petrich 
 - New York  John Wiley & Sons  1977 
 - 168 p  fig  24 cm 
<br/><br/> Contine bibliogr. si index 
<br/><br/><label>ISBN: </label>0471995142 
<br/><br/><label>Dewey Class. No.: </label>512'.2