TY - JOUR TI - The distance to operators with a fixed index T3 - Acta scientiarum mathematicarum AU - Bouldin Richard PY - 1990 LA - English SN - 0001-6969 UR - http://acta.bibl.u-szeged.hu/15264/1/math_054_fasc_001_002_139-143.pdf ER -