@article{MAN_1982__260_163652,
     author = {Patrick Eberlein},
     title = {A {Canonical} {Form} for {Compact} {Nonpositively} {Curved} {Manifolds} {Whose} {Fundamental} {Groups} {Have} {Nontrivial} {Center.}},
     journal = {Mathematische Annalen},
     pages = {23--30},
     publisher = {mathdoc},
     volume = {260},
     year = {1982},
     zbl = {0468.57014},
     url = {http://geodesic.mathdoc.fr/item/MAN_1982__260_163652/}
}