Feb 24, 2018:

https://www.reuters.com/article/us-olympics-2018-doping/russian-bobsledder-sergeeva-admits-anti-doping-violation-cas-idUSKCN1G808W

Feb 18, 2018:

http://abcnews.go.com/Sports/wireStory/column-cheating-russians-olympics-53193119

Feb 9, 2018:

Why Russian athletes are competing as "OARs" at the Winter Olympics | Vox

Feb 5, 2018:

IOC refuses Russian athletes' request to join Winter Olympics | CNN

Feb 1, 2018:

Olympic doping ban overturned for 28 Russian athletes | CNN

Dec 5, 2017:

International Olympic Committee (IOC) President Thomas Bach announced that the Russian Olympic Committee has been banned from participation in the 2018 Winter Olympics scheduled to begin in Pyeongchang, South Korea on February 9.

In the announcement, Bach referred to Russia's involvement as "an unprecedented attack on the integrity of the Olympic Games and sport".

The announcement stated that individual Russian athletes who are found to be "clean" will be allowed to participate, but as an "Olympic Athlete from Russia" (OAR) and not as part of a Russian olympic team.

The ban is a result of a 17-month investigation led by former Swiss president Samuel Schmid which cited "systemic [state-sponsored] manipulation of the anti-doping rules and system" at the 2014 Olympics in Sochi, Russia.

Read the 30-page "IOC Disciplinary Commission's Report to the IOC Executive Board" here.

The investigation came about as a result of the Russian "whistle-blower" doctor Grigory Rodchenkov, who was director of Russia's anti-doping laboratory during the 2014 Sochi Olympic Games.

Russia Is Banned From 2018 Olympics; Athletes Told To Compete Under Olympic Flag | NPR

Russian doping: IOC bans Russia from 2018 Winter Olympics | BBC

Russia Banned From Winter Olympics by I.O.C. | The New York Times