Koskinen, E A
Alen, M
Väärälä, E M
Rellman, J
Kallinen, M
Vainionpää, A
Article History
Received: 9 April 2014
Revised: 28 May 2014
Accepted: 8 July 2014
First Online: 12 August 2014
Competing interests
: The authors declare no conflict of interest.