Article History
Received: 29 May 2018
Accepted: 4 December 2018
First Online: 12 December 2018
Compliance with ethical standards
:
: Hristina Uzunova, Sandra Schultz, Heinz Handels and Jan Ehrhardt declare that they have no conflict of interest.
: This article does not contain any studies with human participants or animals performed by any of the authors.
: For this type of study, formal consent is not required.