BBC News youtube video - Tiananmen Square: What happened in the protests of 1989?
Wikipedia - https://en.wikipedia.org/wiki/1989_Tiananmen_Square_protests
Amnesty International - https://www.amnesty.org.uk/china-1989-tiananmen-square-protests-demonstration-massacre
Washington Post - https://www.washingtonpost.com/graphics/2019/opinions/global-opinions/tiananmen-square-a-massacre-erased/