TY  - BOOK
AU  - Ullman,Edward Louis
TI  - American commodity flow: a geographical interpretation of rail and water traffic based on principles of spatial interchange 
PY  - 1957///
CY  - Seattle
PB  - University of Washington Press
KW  - Transportation
KW  - United States
KW  - Commerce
N1  - Includes bibliographical references (p. 207-213) and index
ER  -