Zhdanovich, V. F. Solution of nonself-adjoint mixed problems by the Fourier method for hyperbolic systems on the plane. III. (Russian) Zbl 0104.07004 Mat. Sb., N. Ser. 49(91), 233-266 (1959). MSC: 35L40 PDFBibTeX XMLCite \textit{V. F. Zhdanovich}, Mat. Sb., Nov. Ser. 49(91), 233--266 (1959; Zbl 0104.07004)
Čulík, Karel Über die lexikographische Summe der teilweise geordneten Mengen. (Czech. Russian, German summaries) Zbl 0085.03801 Čas. Mat. 84, 16-30 (1959). Reviewer: G. Kurepa MSC: 03E20 06A06 PDFBibTeX XMLCite \textit{K. Čulík}, Čas. Pěstování Mat. 84, 16--30 (1959; Zbl 0085.03801)
U, Čžun-chaĭ The Cauchy problem for some degenerate hyperbolic 4th-degree equations. (Russian) Zbl 0084.09101 Science Record, n. Ser. 3, 49-54 (1959). MSC: 35L30 PDFBibTeX XMLCite \textit{Č.-c. U}, Science Record, n. Ser. 3, 49--54 (1959; Zbl 0084.09101)