共 11 条
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[2]
*ASS AM RAILR, 1973, YB RAILROAD FACTS
[3]
NICHOLS RQ, 1971, 15 N DAK STAT U UPP
[4]
PERLE ED, 1964, 95 U CHIC DEP GEOGR
[5]
*US ARMY CORPS ENG, 1971, WATERBORNE COMMERC 2
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*US DEP AGR AGR MA, 1973, RAILR TRANSP COST SU
[7]
*US INT COMM COMM, 1971, 153 71 STAT
[8]
*US INT COMM COMM, 1973, ICI 70 STAT
[9]
*US TAR COMM, 1922, PRE TRANSP RAT REL I
[10]
*WAT FREIGHT BUR, 1972, BARGELOAD BULK G S41