@article{10_1090_S0894_0347_05_00497_2,
     author = {Liu, Chiu-Chu Melissa and Yau, Shing-Tung},
     title = {Positivity of quasi-local mass {II}},
     journal = {Journal of the American Mathematical Society},
     pages = {181--204},
     publisher = {mathdoc},
     volume = {19},
     number = {1},
     year = {2006},
     doi = {10.1090/S0894-0347-05-00497-2},
     url = {http://geodesic.mathdoc.fr/articles/10.1090/S0894-0347-05-00497-2/}
}