1. Bitsadze, A.V., On the structural properties of solutions of hyperbolic systems
of partial differential equations, Mat. Model., 1994,
vol. 6, no. 6, pp. 22–31.
2. Chekmarev, T.V., Formulas for solving the Goursat problem for one linear
system of partial differential equations, Differ. Uravn.,
1982, vol. 18, no. 9, pp. 1614–1622.
3. Pleshchinskaya, I.E., On the equivalence of some classes of first-order elliptic
and hyperbolic systems and second-order partial differential equations, Differ. Uravn., 1987, vol. 23, no. 9,
pp. 1634–1637.
4. Mironova, L.B., On the Riemann method in $$\mathbb {R}^n
$$ for one system with multiple characteristics,
Russ. Math., 2006, vol. 50, no. 1,
pp. 32–37.
5. Zhegalov, V.I. and Mironova, L.B., One system of equations with double
major partial derivatives, Russ. Math., 2007, vol. 51,
no. 3, pp. 9–18.