1. A. M. Nakhushev, “One approximate method for the solution of boundary-value problems for differential equations and its application to dynamics of soil moisture and underground waters,” Differents. Uravn.,
18, No. 1, 72–81 (1982).
2. B. I. Ptashnik, Ill-Posed Boundary-Value Problems for Partial Differential Equations [in Russian], Naukova Dumka, Kiev (1984).
3. Z. A. Nakhusheva, “One nonlocal problem for equations with partial derivatives,” Differents. Uravn.,
22, No. 1, 171–174 (1986).
4. S. V. Zhestkov, “The Goursat problem with integral boundary conditions,” Ukr. Mat. Zh., 42, No. 1, 132–135 (1990);
5. English translation: Ukr. Math. J., 42, No. 1, 119–122 (1990).