Yuri Bolshakov, Cornelis V. M. van der Mee, André C. M. Ran, Boris Reichstein, Leiba Rodman. Extension of Isometries in Finite-Dimensional Indefinite Scalar Product Spaces and Polar Decompositions. SIAM J. Matrix Analysis Applications, 18(3):752-774, July 1997. [doi]
Abstract is missing.