Erlander, Sven <br/><br/>
Optimal spatial interaction and the gravity model  / 

 - Berlin:  Springer-Verlag,  1980 
 - 107p. Index, Bibl. 
 - Lecture notes in Economics and Mathematical Systems ; 173 .
<br/><br/><label>Dewey Class. No.: </label>309.50184  / Er69.OS