an Entity references as follows:
The 2011 ATP World Tour was the elite men's professional tennis circuit organized by the Association of Tennis Professionals (ATP) for the 2011 season. It was the 42nd edition of the tour and the calendar comprised the Grand Slam tournaments, supervised by the International Tennis Federation (ITF), the ATP World Tour Masters 1000, the ATP World Tour 500 series, the ATP World Tour 250 series, the ATP World Team Championship, the Davis Cup (organized by the ITF), and the ATP World Tour Finals. Also included in the 2011 calendar is the Hopman Cup, which does not distribute ranking points, and is organized by the ITF.