1. Agmon, S., Douglis, A, Nirenberg, L.: Estimates near the boundary for solution if elliptic patial differential equations satisfying general boundary conditions, I, II. Comm. Pure Appl. Math. 12 (1959), 623–727;
2. Agmon, S., Douglis, A, Nirenberg, L.: Estimates near the boundary for solution if elliptic patial differential equations satisfying general boundary conditions, I, II. Comm. Pure Appl. Math. 17 (1964), 35–92.
3. Bojarski, B.: Theory of generalized analytic vectors. Ann. Polon. Math. 17 (1966), 281–320 (Russian).
4. Crodel, A.: Sätze vom Cauchy-Kowalewskaja-Typ für partielle komplexe Differentialgleichungssysteme in Klassen verallgemeinerter analytischer Vektoren. Thesis ( Dissertation A ), Halle University, 1986.
5. Douglis, A., Nirenberg, L.: Interior estimates for elliptic systems of partial differential equations. Comm. Pure Appl. Math. 8 (1955), 503–538.