@article{CRMATH_2008__346_5-6_253_0,
     author = {Gendron, T.M.},
     title = {The external fundamental group of an algebraic number field},
     journal = {Comptes Rendus. Math\'ematique},
     pages = {253--256},
     publisher = {Elsevier},
     volume = {346},
     number = {5-6},
     year = {2008},
     doi = {10.1016/j.crma.2008.01.024},
     language = {en},
     url = {http://www.numdam.org/articles/10.1016/j.crma.2008.01.024/}
}