@article{10_2298_FIL2219767T,
     author = {Xiaoyi Tian and Qingxiang Xu},
     title = {A note on extreme points in the closed unit ball of upper triangular 2 {\texttimes} 2 matrices over a {C} * -algebra},
     journal = {Filomat},
     pages = {6767 },
     year = {2022},
     volume = {36},
     number = {19},
     doi = {10.2298/FIL2219767T},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.2298/FIL2219767T/}
}