1. CMAFCIO, Universidade de Lisboa, Portugal
2. Lavrentyev Institute of Hydrodynamics SB RAS, Novosibirsk, Russia. E-mail: antontsevsn@mail.ru
3. FCT, Universidade do Algarve, Portugal. E-mail: holivei@ualg.pt
4. Al-Farabi Kazakh National University, Kazakhstan. E-mail: konat_k@mail.ru