Exterior differential systems / 
R. L. Bryant ... [et al.] 
 - New York :  Springer-Verlag,  1991 
 - 475 p. :  ill. ;  24 cm. 
 - Mathematical Science research Institute Publication ;  18 .
<br/><br/>Includes bibliographical references (p. 462-470) and index 
<br/><br/><label>ISBN: </label>0387974113 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Exterior differential systems<br/>Differential equations, Partial