http://nativeamericannetroots.net/diary/938
http://www.mesoballgame.org/ballgame/ (You will need a Adobe Flash for this site).
https://www.atlasobscura.com/articles/meso-american-baseball (a pop-up window may appear, click on the "X" in the upper righthand corner and the article should appear)
http://mexicounexplained.com/the-mesoamerican-ballgame/