Comment on revised quasilinear equations dealing with wave-number spectra†

We wish to point out that the revised quasilinear equations found recently by Klozenberg & Bernstein (1970) for continuous wave-number spectra, which are a simplified version of those derived by us for discrete wave spectra (Abraham-Shrauner 1970), can be derived easily from the conventional quasilinear equations (Drummond & Pines 1962; Vedenov, Veliklov & Sagdeev 1962) by analytic continuation. The analytic continuation is the same type used in discussions of the plasma dispersion relation for the linearized Vlasov equation and of the weakly unstable kinetic equation (Balescu 1963; Rogister & Obermann 1969).