@article{10_1017_S0017089500002019,
     author = {Au-Yeung, Yik-Hoi and Yuen, Tai-Kwok},
     title = {A characterization of the definiteness of a {Hermitian} matrix},
     journal = {Glasgow mathematical journal},
     pages = {1--4},
     year = {1974},
     volume = {15},
     number = {1},
     doi = {10.1017/S0017089500002019},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089500002019/}
}