Source:
Proceedings of the International Scientific Conference of Daugavpils University / Daugavpils Universitates Starptautiskas Zinatniskas Konferences Materiali; 2014, Issue 56, p121-128, 8p
Source:
Proceedings of the International Scientific Conference of Daugavpils University / Daugavpils Universitates Starptautiskas Zinatniskas Konferences Materiali; 2014, Issue 56, p324-330, 7p