Krupchyk, Katsiaryna; Tuomela, Jukka The Shapiro-Lopatinskij condition for elliptic boundary value problems. (English) Zbl 1162.35360 LMS J. Comput. Math. 9, 287-329 (2006). MSC: 35J55 13P10 35N10 35B30 PDFBibTeX XMLCite \textit{K. Krupchyk} and \textit{J. Tuomela}, LMS J. Comput. Math. 9, 287--329 (2006; Zbl 1162.35360) Full Text: DOI Link
Johnson, Joseph Systems on n partial differential equations in n unknown functions: The conjecture of M. Janet. (English) Zbl 0405.12022 Trans. Am. Math. Soc. 242, 329-334 (1978). MSC: 12H20 12H05 13N05 35R20 35B30 PDFBibTeX XMLCite \textit{J. Johnson}, Trans. Am. Math. Soc. 242, 329--334 (1978; Zbl 0405.12022) Full Text: DOI