Haynes, Kingsley E. <br/><br/>
Gravity and spatial interaction models 
Kingsley E. Haynes 
 - Beverly Hills  Sage Publications  1984 
 - 87 p. ; 22 cm. 
 - Scientific geography series  2 .
<br/><br/>p.80-87 
<br/><br/><label>ISBN: </label>0803925441 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Space in economics--Mathematical models