Sahi, Helka
Sihto, Harri
Artama, Miia
Koljonen, Virve
Böhling, Tom
Pukkala, Eero
Article History
Received: 19 July 2016
Revised: 25 October 2016
Accepted: 3 November 2016
First Online: 15 December 2016
Competing interests
: The authors declare no conflict of interest.