US mainstream news outlets like CBS News with actual reporters on the ground at the time: https://www.cbsnews.com/news/there-was-no-tiananmen-square-massacre/
Classified US communications with assets on the ground: https://wikileaks.org/plusd/cables/89BEIJING18828_a.html
Image Analysis
From your CNN link:
Saying that the "Tiananmen Square massacre" killings actually happened in other parts of the city may be an important academic distinction, but it isn't a particularly stirring defense of the army's actions.
Considering this is the image of Tiananmen that lives in the western popular consciousness, I think there is real value in deconstructing this myth though. When I learned that western journalists are all in agreement that no massacre took place in the square itself, I became more interested in researching the events myself because other Western views concerning what happened could also be misleading or outright lies
spoiler
they were