@article{10_1017_S0017089500001403,
     author = {Bonsall, F. F. and Stirling, D. S. G.},
     title = {Square roots in {Banach} *-algebras},
     journal = {Glasgow mathematical journal},
     pages = {74--74},
     year = {1972},
     volume = {13},
     number = {1},
     doi = {10.1017/S0017089500001403},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089500001403/}
}