@article{10_4064_fm_129_3_181_197,
     author = {Gert Denk and Wolfgang Metzler},
     title = {Nielsen reduction in free groups with operators},
     journal = {Fundamenta Mathematicae},
     pages = {181--197},
     publisher = {mathdoc},
     volume = {129},
     number = {3},
     year = {1988},
     doi = {10.4064/fm-129-3-181-197},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/fm-129-3-181-197/}
}