Ibidem is not recommended by New Hart's Rules. I quote the 2nd ed. (2014):

> "Certain Latin words or their abbreviations have been traditionally used to make citations in notes more concise. These abbreviations serve admirably in print but are far less useful in electronic formats, where the notes may appear (for example) in a pop-up rather than in a consecutive list. The reader hovering on a note link and receiving the abbreviation ‘Ibid.’ in a standalone pop-up gains no useful information. For this reason Oxford prefers the author and short-title system wherever possible. Exceptions are allowed for some specialist material (such as legal publications) where these abbreviations are rigidly followed throughout a discipline" (338).

Again:

> "‘Ibid.’ is best avoided in favour of an author and short-title system" (p. 338)