"Who can recommend good books/articles on negotiation?"

The best book on negotiation, bar none, is "Bargaining for Advantage : Negotiation Strategies for Reasonable People" By Richard Shell. http://www.amazon.com/Bargaining-Advantage-Negotiation-Strat... (looks like it is out of print, but used copies seem cheap enough)

The best book on negotiation is Bargaining for Advantage by G. Richard Shell from Wharton. I would reading Getting to Yes first to get the basics though.

http://www.amazon.com/Bargaining-Advantage-Negotiation-Strat...

http://www.amazon.com/Getting-Yes-Negotiating-Agreement-With...