Pronin, O.
Seidel, M.
Lücking, F.
Brons, J.
Fedulova, E.
Trubetskov, M.
Pervak, V.
Apolonski, A.
Udem, Th.
Krausz, F.
Article History
Received: 20 November 2014
Accepted: 20 March 2015
First Online: 5 May 2015
Competing interests
: The authors declare no competing financial interests.