Humboldt University, Berlin (Germany),
University of Oslo (Norway),
Perimeter Institute (Canada),
University of Basque Country (Spain),
Tufts University (USA),
Arizona State University (USA),
Indiana University (USA),
University of Cambridge (England),
University of Sussex (England),
University of Portsmouth (England),
University of Glasgow (Scotland),
University of Cologne (Germany),
Max-Planck Institute for Gravitational Physics, Golm (Germany),
DESY, Zeuthen (Germany),
Kharkov Institute of Physics and Technology (Ukraine),
Bogolyubov Institute for Theoretical Physics, Kiev (Ukraine),
Bogolyubov Laboratory for Theoretical Physics, Dubna (Russia),
Copernicus Center for Interdisciplinary Studies, Kraków (Poland).