RT Journal Article T1 Approximation by ck-functions - Preliminary report A1 Llavona, José G. PB American Mathematical Society SN 0002-9920 YR 1975 FD 1975 LK https://hdl.handle.net/20.500.14352/64672 UL https://hdl.handle.net/20.500.14352/64672 DS Docta Complutense RD 19 abr 2025