@article{10_4153_CJM_1994_027_4,
     author = {Cohn, Paul M. and Reutenauer, Christophe},
     title = {A {Normal} {Form} in {Free} {Fields}},
     journal = {Canadian journal of mathematics},
     pages = {517--531},
     year = {1994},
     volume = {46},
     number = {3},
     doi = {10.4153/CJM-1994-027-4},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1994-027-4/}
}