Why evaluate legal information?

In this video, a year 3 LLB student who is preparing a term paper with a substantial research component regularly consults his supervisor. In a recent meeting, the supervisor queries why two pieces of information were cited in his draft. One piece of information is from a local real estate agent’s website summarizing the legal provision for the Hong Kong deed of mutual covenant agreements. Another piece of information is a court case covered in a Hong Kong land law blog.