| Clue | Source | Date |
|---|---|---|
| Serena Williams has been its year-end #1 player since 2013 | LA Times Daily | 25 Sep 2016 |
| Serena Williams has been its year-end #1 player since 2013 | ||
| Circuit for Serena and Venus Williams, in brief | New York Times | 01 Nov 2015 |
| Circuit for Serena and Venus Williams, in brief |