How to add citations from research folder

Hello, I am writing a paper. I add links to my research folder and make 2 pages pages open bottom one and above one. then i want to add citations from the research part. is there a way to do it?

Are you referring to formal citations that will be printed in the final paper, or just for your own internal writing process? If the latter, the References sidebar in the Inspector is a good place to stash this kind of stuff, and in fact by default double-clicking on icons of items in the References pane will automatically open an opposing split, or use it if it is available. For formal citations, most people use a citation database in conjunction with Scrivener. They will handle final style guide output, and are just generally easier to use for this sort of thing.