Celebratio Mathematica

A. S. Schwarz: “A few re­marks on the con­struc­tion of solu­tions of non­lin­ear equa­tions,” pp. 124–​128 in Twis­tor geo­metry and non­lin­ear sys­tems (Primor­sko, Bul­garia, Septem­ber 1980). Edi­ted by H.-D. Doeb­n­er and T. D. Palev. Lec­ture Notes in Math­em­at­ics 970. Spring­er (Ber­lin), 1982. MR 699804 Zbl 0522.​47054 incollection