It is the main knock-out competition for russian clubs.
Since 2014 the Super Cup is played between the previous season winner of Premier League and Cup.
In case one team should win both the tournament its opponents in Super Cup will be the Cup finalist.
rrpl.ru/ - Russian Professional League site
www.rugby.ru - Russian union site
rugbyonline.ru - News site about russian rugby
www.rugbystat.droppages.com - Everything about russian and soviet rugby from the origins to 2012
ru.wikipedia.org/wiki/Федерациа_регби_России - Wikipedia pages about russian rugby
Every site was scanned using also web.archive.org