@article{10_4153_CMB_1991_001_2,
     author = {Adachi, Toshiaki},
     title = {Spherical {Mean} and the {Fundamental} {Group}},
     journal = {Canadian mathematical bulletin},
     pages = {3--11},
     year = {1991},
     volume = {34},
     number = {1},
     doi = {10.4153/CMB-1991-001-2},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1991-001-2/}
}