1. Aitchison, J.M., Elliott, C.M. and Ockendon, J.R. (1983) ‘Percolation in Gently Sloping Beaches’, IMA J. App. Math., 30, 269–287.
2. Elliott, C.M. and Friedman, A. (1985) ‘Analysis of a model of percolation in a gently sloping sandbank’, SIAM J. Math. Anal., 16, 941–954.
3. Korobkin, A.A. (1982)‘Formulation of penetration problem as a variational inequality’. Din. Sploshnoi Sredy, 58, 73–79.
4. Howison, S.D., Ockendon, J.R. and Wilson, S.K. (1990) ‘A note on incompressible water entry problems at small deadrise angles’, (Preprint).
5. Elliott, C.M. and Ockendon, J.R. (1982) ‘Weak and Variational Methods for Free and Moving Boundry Problems’, 59, Pitman Research Notes in Math.