@article{MZ_1981__176_183638,
     author = {E.C. Turner and R.Z. Goldstein},
     title = {Reduced {Forms} for {Quadratic} {Words} and {Spines} of 2-manifolds.},
     journal = {Mathematische Zeitschrift},
     pages = {195--198},
     publisher = {mathdoc},
     volume = {176},
     year = {1981},
     zbl = {0432.20032},
     url = {http://geodesic.mathdoc.fr/item/MZ_1981__176_183638/}
}