Ruggiero, Rafael O. <br/><br/>
An introduction to the study of variational and topological aspects of invariant tori of the geodesic flow of surfaces/ 
Rafael O. Ruggiero. 
 - Lima:  IMCA/UNI,  2002. 
 - 65 p.: 
 - Monografias del IMCA;  29 .
<br/><br/><label>ISBN: </label>997289908X