edited by R. E. Bogner and A. G. Constantinides. edited by V. Cappellini and A. G. Constantinides. edited by A. R. Butler and M. J. Perkins. edited by D.G. Jones and D.R. Davies. edited by I. M. Barbour and A. T. Davies. edited by M. Singer and J. P. Schade. edited by D. G. Lainiotis and N. S. Tzannes. edited by A.R. Butler and M.J. Perkinks. edited by B.A.J. Ponder and M.J. Waring. edited by F. A. Skinner and D. W. Lovelock.