Avila, Geraldo S. S. Lectures on the wave equation. (English) Zbl 0247.35073 Sao Paulo: Publicacoes da Sociedade de Matematica. II, 83 p. (1969). MSC: 35-01 35L05 35L15 35G10 PDF BibTeX XML OpenURL
Gollwitzer, H. E. On nonlinear oscillations for a second order delay equation. (English) Zbl 0169.11401 J. Math. Anal. Appl. 26, 385-389 (1969). Reviewer: Herman E. Gollwitzer (Knoxville) MSC: 34K11 PDF BibTeX XML Cite \textit{H. E. Gollwitzer}, J. Math. Anal. Appl. 26, 385--389 (1969; Zbl 0169.11401) Full Text: DOI OpenURL