Ullman Edward L <br/><br/>
American commodity flow   A geographical interpretation of rail and water traffic based on principles of spatial interchange    

 - Seattla  university of Washington Press         1957 
 - xix, 215p  cm. 
<br/><br/><label>Source: </label> General Book 
<br/><br/><label>Dewey Class. No.: </label>U641.73.N5, J7