On the Lidskii--Vishik--Lyusternik Perturbation Theory for Eigenvalues of Matrices with Arbitrary Jordan Structure    Julio Moro, James V. Burke, and Michael L. Overton
SIAM. J. Matrix Anal. & Appl. 18, pp. 793-817
http://epubs.siam.org/simax/resource/1/sjmael/v18/i4/p793_s1?isAuthorized=no