中国科学院数学与系统科学研究院期刊网
The Non-Existence of Expansive Z~2 Actions on Graphs
En Hui SHI(1), Li Zhen ZHOU(2)
Acta Mathematica Sinica, Chinese Series . 2004, (5): 899 -904 .  DOI: 10.12386/A2004sxxb0113