Sirakov, Alexander
Aguilar-Perez, Marta
AlMatter, Muhammad
Henkes, Hans
Article History
Received: 13 October 2019
Accepted: 18 November 2019
First Online: 5 December 2019
Compliance with ethical guidelines
:
: M. Aguilar-Perez has a proctoring and consulting agreement with phenox GmbH. H. Henkes is co-founder and shareholder of phenox GmbH and femtos GmbH. A. Sirakov and M. AlMatter declare that they have no competing interests.