共 31 条
[21]
Richardson D. M., 1997, P535
[22]
Richardson D.M., 1992, P271
[23]
*STATS SA, 1999, RUR SURV 1997
[24]
*STATSSA, 1998, CENS BRIEF
[25]
VERSVELD DB, 1998, 97154 CSIR ENVSC
[26]
VERSVELD DD, 1998, 9998 WRC TT
[27]
*WFWP, 2000, ANN REP 1999 2000
[28]
WFWP, 2000, WORK WAT PROGR MULT
[29]
*WFWP, 1999, ANN REP 1998 1999
[30]
*WFWP, 1998, ENV IMP INV AL PLANT