@article{Han-2013-APS,
	doi = {10.7498/aps.62.110702},
	year = {2013},
	volume = {62},
	pages = {110702},
	author = {Han, W. P. and Shi, Y. M. and Li, X. L. and Luo, S. Q. and Lu, Y. and Tan, P. H.},
	title = {The numerical-aperture-dependent optical contrast and thickness determination of ultrathin flakes of two-dimensional atomic crystals: {A} case of graphene multilayers},
	journal = {Acta Phys. Sin.}
}