Bozhinov, N. S.; Elabd, E. M. Representation of commutants and multipliers related to the nonlocal Sturm-Liouville integro-differential operator, which integral part is of Volterra type. (English) Zbl 1046.47504 Math. Balk., New Ser. 10, No. 1, 133-146 (1996). MSC: 47G20 35J05 47A70 PDFBibTeX XMLCite \textit{N. S. Bozhinov} and \textit{E. M. Elabd}, Math. Balk., New Ser. 10, No. 1, 133--146 (1996; Zbl 1046.47504)
Ewing, R. E.; Margenov, S. D.; Vassilevski, P. S. Preconditioning the biharmonic equation by multilevel iterations. (English) Zbl 1034.65507 Math. Balk., New Ser. 10, No. 1, 121-132 (1996). MSC: 65N06 65N55 65F10 65F35 35J40 PDFBibTeX XMLCite \textit{R. E. Ewing} et al., Math. Balk., New Ser. 10, No. 1, 121--132 (1996; Zbl 1034.65507)