1. Janusz Korczak Memorial Voivodeship Hospital, Słupsk, Poland.
2. Varaždin General Hospital, Varaždin, Croatia.
3. Students' Scientific Association, Department of Neurosurgery, Medical University of Gdansk, Gdansk, Poland.
4. Federal Almazov North-West Medical Research Centre, St. Petersburg, Russia.
5. Poznań University of Medical Sciences, Poznań, Poland.
6. Medical University of Gdansk, Gdansk, Poland.
7. Department of Neurosurgery, Medical University of Gdansk, Gdansk, Poland.