1. I. Gohberg, P. Lancaster, L. Rodman, Matrices and Indefinite Scalar Products, Operator Theory, Advances and Applications, v.8, Birkhaeuser Verlag, 1983.
2. I. Gohberg, P. Lancaster, L. Rodman, Invariant Subspaces of Matrices with Applications, John Wiley and Sons, 1986.
3. I. M. Gel'fand and V. A. Ponomarev, Remarks on the Classification of a Pair of Commuting Linear Transformations in a Finite-dimensional Space, J. Functional Analysis and its Applications, vol.3, no.4, p.p.325?326, 1969.