共 15 条
[3]
COLE DN, 1989, USDA INT259 FOR SERV
[4]
COLE DN, 1982, USDA INT284 FOR SERV
[5]
COLE DN, 1983, USDA INT302 FOR SERV
[6]
COLE DN, 1993, USDA INT464 FOR SERV
[7]
Graefe A. R., 1990, VISITOR IMPACT MANAG, V2
[8]
MARION JL, 1991, USDI NPSNRVTNRR9106
[9]
MARION JL, 1993, USDI NPSNRVTNRR9312
[10]
MARION JL, 1988, USDI MAR36 NAT PARK