Level spacing statistics for two-dimensional massless Dirac billiards
Huang Liang (黄亮), Xu Hong-Ya (徐洪亚), Lai Ying-Cheng (来颖诚), Celso Grebogi
Chin. Phys. B . 2014, (7): 70507 -070507 .  DOI: 10.1088/1674-1056/23/7/070507