@article{10_1017_S0017089500003979,
     author = {Braune, Erhard},
     title = {On the approximation of \ensuremath{\pi} by special algebraic numbers},
     journal = {Glasgow mathematical journal},
     pages = {51--56},
     year = {1980},
     volume = {21},
     number = {1},
     doi = {10.1017/S0017089500003979},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089500003979/}
}