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2. http://www.latimes.com/sports/lakers/lakersnow/la-sp-ln-lakers-pau-gasol-knee-procedure-20130509-story.html
3. http://www.nytimes.com/2013/12/16/sports/tennis/sharapova-is-back-in-the-game-and-as-driven-as-ever.html?pagewanted=all&_r=2&
4. http://www.nytimes.com/2011/05/12/sports/baseball/disputed-treatment-was-used-in-bartolo-colons-comeback.html?pagewanted=1&_r=3&hp
5. Clinical challenges and opportunities of mesenchymal stem cells in musculoskeletal medicine;Centeno;PM R,2014