陕甘宁边区生态购买设计与操作途径
延军平,严艳
Design and Operation Channels of the Ecological Purchase in the Shaanxi-Gansu-Ningxia Border Area
YAN Junping, YAN Yan
地理学报 . 2002, (3): 345 -355 .  DOI: 10.11821/xb200203011