1. R. Agliardi,Cauchy problem for non-kowalewskian equations, Intern. J. Math.,6 (1995), pp. 791–804.
2. R. Aglardi—D. Mari,On the Cauchy problem for some pseudodifferential operators of Schrodinger type, M
3
AS, Math. Mod. Methods Appl. Sci.,6 (1996).
3. R. Agliardi—D. Mari,On the Cauchy problem for some non-Kovalewskian equations in D
2
L
{σ}, Ann. Mat. Pura Appl.,70 (1996), pp. 89–101.
4. F. Cardoso—F. Treves,A necessary condition of local solvability for pseudodifferential equations with double characteristics, Ann. Inst. Fourier, Grenoble,24 (1974), pp. 225–292.
5. L. Cattabriga—D. Mari,Parametrix of infinite order on Gevrey spaces to the Cauchy problem for hyperbolic operators with one constant multiple characteristic, Ricerche Mat.,36, Suppl. (1987), pp. 127–147.