No program code from foldings in articles with foldings https://ru.wikipedia.org/wiki/Одиночка_(шаблон_проектирования). In PDF there are only headers left.
Topic on Talk:Reading/Web/PDF Functionality/Flow
This issue is specific to the russian wikipedia, please contact the administrators of the Russian Wikipedia.
where shuold i contact to? Link for PDF bugs leads here.
I'm not familiar with russian wikipedia, but maybe someone on ru:Википедия:Форум can help you, or at least show you the way.