共 16 条
[11]
*NAT COAL ASS, 1980, INT COAL 1979
[12]
*NAT WAT COMM, 1973, WAT POL FUT
[13]
RAO S, 1977, PTI7706 PENNS TRANSP
[14]
REAGAN R, 1981, 9721 HOUS DOC
[15]
REDDY NN, 1976, Q REV ECON BUS, V16, P51
[16]
WILSON HG, 1979, LOGIST TRANSPORT REV, V15, P401