3Peter E, Liaschenko J. Perils of proximity:a spatiotemporal analysis of moral distress and moral ambiguity [J]. Nursing Inquiry, 2004,11 (4) : 218-225.
4Davies C E, Moss D, Hill M O. EUNIS habitat classification revised 2004[R]. European Environment Agency-European Topic Centre on Nature Protection and Biodiversity, 2004: 127-143.
5Hasan M S. The long-run relationship between population and per capita income growth in China[J]. Journal of Poli- cy Modeling, 2010,32 (3) : 355-372.
6Hering L,Poncet S. Market access and individual wages :Ev- idence from China[J]. The Review of Economics and Statis-ties, 2010,92(1 ) : 145-159.