Here's a good aggregation of sources, many of the mainstream western press:
https://worldaffairs.blog/2019/06/02/tiananmen-square-massacre-facts-fiction-and-propaganda/
some of the lib-friendly sources used:
https://www.cjr.org/behind_the_news/the_myth_of_tiananmen.php
https://www.cbsnews.com/news/there-was-no-tiananmen-square-massacre/