Open (unrestricted) Access

This paper bears the green Open Access logo which means that it was published under the Schweizerbart/Borntraeger open access policy. The paper thus accessible and downloadable without restriction to all interested parties and this open access has been sponsored by the author, institution or other sponsoring entity.

The Schweizerbart/Borntraeger open access program is a reasonably priced way to have the permanent care, long term care and preservation a publisher provides for published contents while at the same time having the paper publicly accessible to the scientific public.