@article{SM_2006_197_10_a6,
     author = {V. L. Kurakin},
     title = {Periodic functions on a free semigroup},
     journal = {Sbornik. Mathematics},
     pages = {1509--1528},
     publisher = {mathdoc},
     volume = {197},
     number = {10},
     year = {2006},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_2006_197_10_a6/}
}