Some professors prefer the use of Ibid. rather than repeated references to the same source.
Ibid. stands for Ibidem, meaning "in the same place."
You use Ibid. when the note immediately preceding it is from the same place.
Be careful about converting your notes to Ibid.s until you are ready to print the final draft of your paper. Otherwise you run the risk of separating your Ibid. from the source it’s linked to if/when you rearrange the order of sentences and paragraphs in early drafts.