@article{MAN_1968__175_161654,
     author = {W. RUCKLE},
     title = {On {Perfect} {Symmetrie} {BK} {Spaces.}},
     journal = {Mathematische Annalen},
     pages = {121--126},
     year = {1968},
     volume = {175},
     zbl = {0156.13305},
     url = {http://geodesic.mathdoc.fr/item/MAN_1968__175_161654/}
}