Powell, M. J. D. <br/><br/>
Approximation theory and methods / 
M. J. D. Powell 
 - Cambridge, U. K. :  Cambridge University Press,  1981 
 - 339 p. :  ill. ;  24 cm. 
<br/><br/><label>ISBN: </label>0521224721 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Approximation theory