Sironi, Silvia
Wagner, Michaela
Kuett, Alexander
Drolle, Heidrun
Polzer, Harald
Spiekermann, Karsten
Rieger, Christina
Fiegl, Michael
Article History
Received: 18 August 2015
Accepted: 3 November 2015
First Online: 30 November 2015
Competing interests
: The authors declare no competing financial interests.