Lijun Yi. (1970). An $L^∞$-Error Estimate for the $h$-$p$ Version Continuous Petrov-Galerkin Method for Nonlinear Initial Value Problems.
            <i>East Asian Journal on Applied Mathematics</i>. <i>5</i> (4).
            301-311.
         doi:10.4208/eajam.310315.070815a