TY - JOUR TI - NP-operators and semi-Carleman operators T3 - Acta scientiarum mathematicarum AU - Wong Tin Kin PY - 1972 LA - English SN - 0001-6969 UR - http://acta.bibl.u-szeged.hu/14343/1/math_033_fasc_001_002_105-112.pdf ER -