Source:
Proceedings of the International Scientific Conference of Daugavpils University / Daugavpils Universitates Starptautiskas Zinatniskas Konferences Materiali; 2014, Issue 56, p72-80, 9p
Source:
Proceedings of the International Scientific Conference of Daugavpils University / Daugavpils Universitates Starptautiskas Zinatniskas Konferences Materiali; 2014, Issue 55, p400-407, 8p