1. M. Mirsaburov, “A Boundary-Value Problem for a Class of Mixed Type Equations with the Bitsadze-Samarskii Condition on Parallel Characteristics,” Differents. Uravneniya 37(9), 1281–1284 (2001).
2. F. Tricomi, Sulle Equazioni Lineari Alle Derivate Parziali di Secondo Ordine, di TipoMisto (Gostekhizdat, Moscow-Leningrad, 1947).
3. A. V. Bitsadze and A. A. Samarskii, “Some Simplest Generalizations of Linear Elliptic Boundary-Value Problems,” Sov. Phys. Dokl. 185(4), 739–740 (1969).
4. F. I. Frankl, “Streamlining of Profiles by a Flowwith a SubsonicVelocity with a Supersonic Zone Ended with a DirectShockWave,” Pril.Mat. Mekh. 20(2), 196–202 (1956).
5. Lin’ Tszyan-bin, “On Some Frankl’s Problems,” Vestnik LGU. Ser. Matem.-Mekh. i Astr., No. 3, 28–39 (1961).