Andrew A.L. Comments on "analytical solutions for thenth derivatives of eigenvalues and eigenvectors for a nonlinear eigenvalue problem" / A. L. Andrew, K. -W.E. Chu, 1989. - 4 p. - Текст : непосредственный.
Andrew A.L. Direct computation of derivatives of eigenvalues and eigenvectors / A.L.Andrew,F.R.de Hoog,R.C.E.Tan, 1990. - 6 p. - Текст : непосредственный.