Some simple, concrete and complete books in their field.

The basic reference "Bibles" :
Management for the dummies - Bob Nelson and Peter Economy
All management theories - Carol Kennedy
Tous innovateurs - Hubert Jaoui (only in french and italian)
Getting to Yes - R. Fisher and W. Ury

Readings with surprisingly diffrent point of views :
Les décisions absurdes – Christian Morel (about wrong decisions)
La décision - (At the boundaries of neuro-sciences) - Alain Berthoz
Emotionnal intelligence volume 2 - Daniel Goleman and Daniel Roche