Birkhoff, G. D. On plates of variable thickness. (English) JFM 48.0941.06 Bull. Am. Math. Soc. 28, 5 (1922). MSC: 34K20 PDFBibTeX XMLCite \textit{G. D. Birkhoff}, Bull. Am. Math. Soc. 28, 5 (1922; JFM 48.0941.06) Full Text: DOI
Birkhoff, G. D.; Langer, R. E. The boundary problems and developments associated with a system of ordinary linear differential equations of the first order. (English) JFM 48.0528.03 Bull. Am. Math. Soc. 28, 236 (1922). MSC: 34-XX PDFBibTeX XMLCite \textit{G. D. Birkhoff} and \textit{R. E. Langer}, Bull. Am. Math. Soc. 28, 236 (1922; JFM 48.0528.03) Full Text: DOI