These files are intended for correct display of days of week in Russian.
Has edited NePriGen, and has helped it Zmey
-------------------------------------------------------------------------
...\root\www\admin\inc\cal.js 
...\root\www\class\Calendar.Class.php 
...\root\www\templates\yours template\calendar\calendar_small.tpl 
...\root\www\templates\yours template\calendar\calendar_small_prev_next.tpl 
...\root\www\templates\yours template\calendar\calendar_small_years.tpl 
--------------------------------------------------------------------------