I recently received a copy of the second edition of Hal Abramson's excellent publication: Mediation Representation. Published by Oxford University Press, this is a comprehensive guide for those representing clients in mediation--and to negotiation generally.
It is written for the market outside North America and the author has sought to be 'culturally neutral' (though with reference to various cultural practices). He has drawn on sources and the work of colleagues far and wide and thus has enriched this valuable text.
My eye was drawn to an appendix discussing decision tree analyses and to the final chapter on breaking impasse. But one has to go back to the start and understand the difference between positional and problem solving approaches to negotiation, covered in chapter one.
There is extensive writing about preparation, critical to successful advocacy in mediation, and the book is full of helpful insights, examples, checklists and references to other excellent sources.