Frentzen, Hilbert On J-symmetric quasi-differential expressions with matrix-valued coefficients. (English) Zbl 0615.34022 Quaest. Math. 10, 153-164 (1986). Reviewer: D.Robert MSC: 34L99 47E05 × Cite Format Result Cite Review PDF Full Text: DOI
Frentzen, Hilbert Limit-point criteria for symmetric and j-symmetric quasi-differential expressions of even order with a positive definite leading coefficient. (English) Zbl 0614.34011 Fachbereich Mathematik der Universität GHS Essen. 66 p. (1985). Reviewer: J.Kalas MSC: 34A30 34C05 × Cite Format Result Cite Review PDF