@article{10_1017_S0017089500003050,
     author = {Sproston, J. P.},
     title = {Derivations and pure states},
     journal = {Glasgow mathematical journal},
     pages = {73--77},
     year = {1977},
     volume = {18},
     number = {1},
     doi = {10.1017/S0017089500003050},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089500003050/}
}