Urazhdin, S.
Demidov, V. E.
Ulrichs, H.
Kendziorczyk, T.
Kuhn, T.
Leuthold, J.
Wilde, G.
Demokritov, S. O.
Article History
Received: 8 November 2013
Accepted: 7 April 2014
First Online: 11 May 2014
Competing interests
: The authors declare no competing financial interests.