-Zotero is legit the best application for keeping your essay sources sorted. If you use chrome or Firefox you can install the add on that will just grab everything off a page or pdf (author, date, title, book #, ect) and add it to the folder of your choice. It also auto creates bibliographies and in text citations for all items you select at a time. (I used to dread sourcing things because there wasn't a good site to help keep track of it all, and now with zotero I'm actually drowning in too many sources).
-Cant write a section in your story? Placeholder the paragraph with a summary of what you want to happen and move to a different scene that comes easier to you at that time.