@article{MAN_1966__166_161458,
     author = {R.C. LYNDON},
     title = {On {Dehn's} {Algorithm.}},
     journal = {Mathematische Annalen},
     pages = {208--228},
     publisher = {mathdoc},
     volume = {166},
     year = {1966},
     zbl = {0138.25702},
     url = {http://geodesic.mathdoc.fr/item/MAN_1966__166_161458/}
}