van der Harg, J M
Nölle, A
Zwart, R
Boerema, A S
van Haastert, E S
Strijkstra, A M
Hoozemans, J JM
Scheper, W
Article History
Received: 22 April 2014
Revised: 11 July 2014
Accepted: 23 July 2014
First Online: 28 August 2014
Competing interests
: The authors declare no conflict of interest.