@article{article890f75a7,
title   = {Roots of mappings on nonorientable surfaces and equations in free groups},
author = {Gonçalves, Daciberg Lima and Kudryavtseva, Elena A and Zieschang, Heiner},
year = {2002},
doi = {10.1007/s002290100238},
journal   = {Manuscripta Mathematica}
}