The procedure of this collection is as follows: one or several coordinators will outline a very specific problem of their investigation. Immediately afterwards, they will invite other experts to present a new article which responds to the mentioned problem.

The book will consist of three parts. The first part will be the article of the coordinators which presents the theme of the investigation. The second part will be formed by the articles provided by the guest investigators. In the third and last part, the coordinators will make an analysis of the problem and they will establish a status of the issue which may be revised in the following reeditions in the light of new contributions, either from the guests themselves or through the new incorporations accepted by the coordinators.