Text and Data Mining valid from 2019-12-20
Received: 29 September 2019
Accepted: 26 November 2019
First Online: 20 December 2019
Compliance with ethical guidelines
: H. Frohnhofen, R. Popp, S. Stieglitz, N. Netzer and H. Danker-Hopfe declare that they have no competing interests.
: For this article no studies with human participants or animals were performed by any of the authors. All procedures reported in this article were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.