Maslov, V. P. The complex WKB method in nonlinear equations. (Kompleksnyj metod VKB v nelinejnykh uravneniyakh). (Russian) Zbl 0449.58001 Nelinejnyj Analiz i ego Prilozheniya. Moskva: Izdatel’stvo “Nauka”. 384 p. R. 1.60 (1977). MSC: 58-02 37J99 35Q99 81T99 81Q99 53D50 58J40 70H99 PDFBibTeX XML
Volobuev, I. P. On a consequence of the causality condition in field theory with a momentum space of constant curvature. (English) Zbl 0412.53015 Theor. Math. Phys. 28, 822-828 (1977). MSC: 53B50 81T99 51M10 PDFBibTeX XMLCite \textit{I. P. Volobuev}, Theor. Math. Phys. 28, 822--828 (1977; Zbl 0412.53015) Full Text: DOI