@article{MZ_1974__136_172028,
     author = {Alfred Pietrowski},
     title = {The {Isomorphism} {Problem} for {One-relator} {Groups} with {Non-trivial} {Centre.}},
     journal = {Mathematische Zeitschrift},
     pages = {95--106},
     publisher = {mathdoc},
     volume = {136},
     year = {1974},
     zbl = {0264.20029},
     url = {http://geodesic.mathdoc.fr/item/MZ_1974__136_172028/}
}