Badea, C.; Badea, I.; Cottin, C. A Korovkin-type theorem for generalizations of Boolean sum operators and approximation by trigonometric pseudopolynomials. (English) Zbl 0671.42003 Math., Rev. Anal. Numér. Théor. Approximation, Anal. Numér. Théor. Approximation 17, No. 1, 7-17 (1988). Reviewer: S.M.Shah MSC: 42A10 41A36 PDFBibTeX XMLCite \textit{C. Badea} et al., Math. Rev. Anal. Numér. Théor. Approximation, Anal. Numér. Théor. Approximation 17, No. 1, 7--17 (1988; Zbl 0671.42003)
Badea, Ion; Badea, Cătălin On the order of simultaneous approximation of bivariate functions by Bernstein operators. (English) Zbl 0638.41018 Math., Rev. Anal. Numér. Théor. Approximation, Anal. Numér. Théor. Approximation 16, 11-17 (1987). MSC: 41A36 41A28 PDFBibTeX XMLCite \textit{I. Badea} and \textit{C. Badea}, Math. Rev. Anal. Numér. Théor. Approximation, Anal. Numér. Théor. Approximation 16, 11--17 (1987; Zbl 0638.41018)
Badea, Ion; Andrica, Dorin Voronovskaja-type theorems for a certain non-positive linear operator. (English) Zbl 0616.41017 Math., Rev. Anal. Numér. Théor. Approximation, Anal. Numér. Théor. Approximation 15, 95-103 (1986). Reviewer: R.Precup MSC: 41A36 41A10 PDFBibTeX XMLCite \textit{I. Badea} and \textit{D. Andrica}, Math. Rev. Anal. Numér. Théor. Approximation, Anal. Numér. Théor. Approximation 15, 95--103 (1986; Zbl 0616.41017)