Ritt J.F. <br/><br/>
Differential algebra. 
Ritt J.F. 
 - New York  Amer. Math. Soc.  1950 
 - 192 p. 
<br/><br/> American Mathematical Society, Colloquium Publications, Vol. 33 
<br/><br/><label>Dewey Class. No.: </label>517.911