I'd like to know your opinion on citations in abstracts. At my university, there is no rule on that matter so it's basically a question of preference.
Do you think it's okay to have citations in an abstract or do you personally prefer to have the abstract be a ``stand-alone'' piece of work?
It depends on the situation.
An abstract for a paper must be stand-alone, because the bibliography is hidden in the paper itself. The abstract must contain all information required for people to judge if they want to read the paper, and as there is no bibliography, the reader does not know what the citations relate to. Therefore, there should be no citations.
It may be a bit different if the abstract is for a conference. Maybe in some situations it's possible to add one or two references at the end of the abstract. In that case, it can be okay to have citations.
So the most important question here is: can the reader use the abstract as a stand-alone unit? If using citations cause the answer to this question to be no, don't do citations.