@article{Neumann33,
     author  = {Bernd Neumann},
     title   = {Die {A}utomorphismengruppe der freien {G}ruppen},
     journal = {Math. Annalen},
     volume  = 107,
     year    = 1933,
     pages   = {367--386} }

@article{BirgetEtAl00,
     author  = {J.-C. Birget and S. Margolis and J. Meakin and P. Weil},
     title   = {{PSPACE}-complete problems for subgroups of free groups
                and inverse finite automata},
     journal = {Theoretical Computer Science},
     volume  = 242,
     year    = 2000,
     pages   = {247--281} }

@book{LyndonSchupp77,
     author  = {Roger C. Lyndon and Paul E. Schupp},
     title   = {Combinatorial Group Theory},
     publisher = {Springer},
     year    = 1977 },

@mastersthesis{Sievers03,
     author  = {Christian Sievers},
     title   = {Algorithmen f\accent127ur freie {G}ruppen},
     school  = {TU Braunschweig},
     year    = 2003,
     type    = {Diplomarbeit} }

@article{Nielsen,
     author  = {J. Nielsen},
     title   = {Die {I}somorphismengruppe der freien {G}ruppen},
     journal = {Math. Annalen},
     volume  = 91,
     year    = 1924,
     pages   = {169--209} }
