Penrose, Roger, <br/><br/>
Techniques of differential topology in relativity 
Roger Penrose. 
 - Philadelphia  Society for Industrial and Applied Mathematics  1972. 
 - 72 pages :  illustration, ;  25 cm. 
<br/><br/>p. 72 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Relativity (Physics)<br/>Space and time