1. Reducing Heegaard splittings;Casson;Top. and Appl.,1987
2. Dehn surgery on knots;Culler;Ann. Math.,1987
3. On primitive sets of loops in the boundary of a handlebody;Gordon;Top. and Appl.,1987
4. J. Hass and B. Wajnryb: Invariants of oriented knots and links, preprint.
5. J. Hempel and L. Roeling: Free factors of handlebody groups, preprint.