My university (UCL) defines primary sources as things that are contemporary to the time period in question: So, when I was writing my paper on the political effectiveness of the title "King of Babylon" to the Neo-Assyrian rulers of the tenth dynasty, they liked it when I cited the State Archives of Assyria (SAA), which is made up of legal documents as well as diplomatic and political correspondence and cultic prophecies.

So, if I was to make a guess on what your professor wants of primary sources, then newspaper articles might be one of those things. You might also want to look up anything you can on official statements from Beijing relating to Hong Kong, and citing those directly. (I know, for instance, each UN delegation has their own website where they publish their responses to issues in each chamber and such. I don't know if Chinese ministries do the same thing or not).

Sadly, as an Ancient Historian, there's nothing I can point you to directly. I hope this gives you some ideas, though.

A primary source is anything that directly reflects the time, place, and people when/by whom it was written. This doesn't necessarily mean just a newspaper article that was written immediately after the fact. For example, an article with headline like "Speech by So-and-So highlights new direction in policy", there's an argument to be made that it could be used as a secondary source: somebody who knows the old policy analyzing the effect of an event on new policy. In that case, the speech itself would be the best primary source.

Now, to go a step further, that same article could also be a primary source if you were looking at how policy changes are reported in media. How you use a source can change whether it is primary or secondary.

Try to get sources that are as close to the events as possible. If a newspaper is describing events on the ground as they unfold, that's probably a primary source. But newspapers aren't the only possible primary sources. Maybe there were bloggers close to/at the scene who reported their first-hand account of the events? Maybe someone has written a memoir? I would argue that even things like tweets could be primary sources. What about manifestos published by the protesters? Or policy statements given by the government? Protest signs, songs, graffiti? These are all possible primary source material

But, never forget to consider the source of your source, as it were. Were they pro-demonstrator or pro-government? Were they young or old? Were they a student, a businessperson or a professional activist? All of those things should be taken into consideration when you analyze your source and should effect how much/if you believe them. It can and should also impact how you use the source material itself.

Good luck on your paper.