Authors: Zhang Peng¹, Zuo Chun-cheng¹ zuocc@jlu.edu.cn, Zhou De-yi²

Superior Title: Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban. 2009, Vol. 41 Issue 9, p169-172. 4p. 1 Diagram, 6 Graphs.