1. P.A. Binding and Q. Ye, Variational principles without definiteness conditions, preprint.
2. A minimax theory for overdamped networks;Duffin;Arch. Rational Mech. Anal.,1955
3. Matrices and Indefinite Scalar Products;Gohberg,1983
4. P. Lancaster and Q. Ye, Variational properties and Rayleigh quotient algorithm for symmetric matrix pencils, in Oper. Theory Adv. Appl. 40, Birkhäuser, Basel, pp. 247–278.
5. A minimax characterization for the eigenvalues of a positive symmetric operator in a space with an indefinite metric;Phillips;J. Fac. Sci. Univ. Tokyo Sect. IA Math.,1970