@article {10833,
	title = {Persistent spin current in nanodevices and definition of the spin current},
	journal = {Physical Review B - Condensed Matter and Materials Physics},
	year = {2008},
	doi = {10.1103/PhysRevB.77.035327},
	author = {Qing-Feng Sun and X.C. Xie and Jian Wang}
}
