Text and Data Mining valid from 2018-02-28
Received: 16 January 2018
Accepted: 22 February 2018
First Online: 28 February 2018
Compliance with ethical standards
: Zuzanna Małgorzata Łukasik declares that she has no conflict of interest. Marcin Makowski declares that he has no conflict of interest. Joanna Samanta Makowska declares that she has no conflict of interest.
: This article does not contain any studies with human participants performed by any of the authors.