TY - JOUR TI - Arithmetics in free semigroups T3 - Acta scientiarum mathematicarum AU - Pollák György PY - 2002 LA - English SN - 0001-6969 UR - http://acta.bibl.u-szeged.hu/15902/1/math_068_numb_001_002_107-115.pdf ER -