Egger, Jan
Schmalstieg, Dieter
Chen, Xiaojun
Zoller, Wolfram G.
Hann, Alexander http://orcid.org/0000-0001-8035-3559
Article History
Received: 14 October 2016
Accepted: 20 March 2017
First Online: 18 April 2017
Competing Interests
: The authors declare that they have no competing interests.