Poulsen Nautrup, Hendrik http://orcid.org/0000-0001-7815-7006
Friis, Nicolai http://orcid.org/0000-0003-1950-8640
Briegel, Hans J.
Article History
Received: 20 March 2017
Accepted: 14 September 2017
First Online: 6 November 2017
Competing interests
: The authors declare no competing financial interests.