Q: How to write an abstract with multiple literature from multiple sources?
Your question does not have any details, so it is difficult to understand what exactly you mean and why you would need to include literature from multiple sources in your abstract.
An abstract is a short summary of a paper that tells the readers what each section of the paper contains, so that readers can form a clear view on what to expect from the paper and whether they should read the entire paper.
An abstract explains why the research was conducted, what the aims were, how these were met, and what the main findings were. Thus, it briefly mentions the main objectives and hypothesis of the study, the methodology used, the main results, and a concluding statement. An abstract should not include a literature review. Thus, I am not sure why you wish to include references to multiple literature in your abstract, unless your manuscript is a review article. In case you are writing the abstract for a narrative review article, here's how you should go about:
- Begin with one or two sentences of background information on the topic being discussed in the review.
- Next, briefly state the aim of the review.
- This should be followed by a description of the methods you have used to conduct your review – you need to specify which databases you have searched, how many articles you have reviewed, the time-frame of the articles.
- Next, state the main observations you have made from the literature review you have conducted (2-3 sentences)
- The concluding remarks should state your opinion about the findings from the literature review. You can make close the abstract by stating the larger implications of the findings.