[MathOuvrage]
Linear differential operators
/ Lanczos, Cornelius.
-Philadelphia PA : Society for industrial and applied mathematics, 1996. - xvii, 564 p. ; 23 cm
[MathOuvrage]
Wave propagation
/ Ed. Birman, M. Sh..
-Providence RI : American mathematical Society, 1993. - x, 256 p. ; 26 cm