Zdzislaw Jackiewicz Bruno D. Welfert Stability of Gauss-Radau Pseudospectral Approximations of the One-Dimensional Wave Equation. 287-313 2003 18 J. Sci. Comput. 2 https://doi.org/10.1023/A:1021121008091 db/journals/jscic/jscic18.html#JackiewiczW03