✔ 最佳答案
If you were using in-text citations, you could use Ibid and the page numbers.
In the bibliography, you may have three options. The first is to list it three times, changing the page numbers. The second is to list them consecutively, using "Ibid., 6-8." The third is "Rowling 1997, 6-8."
If it were me, I would take two minutes and contact the professor stating that I found all three options and wanted to use the correct one. I would write out exactly what the three options are so the professor can respond "Use the third one" and be done.