Aggregators offer ebooks on one platform from a number of publishers. Which one to select? Look at the coverage description for the collection. If not clear, Proquest's Ebook Central can be a good place to start for more current scholarship.
Do you know the book's publisher? You may be able to access the e-book directly from the publisher's platform (via NYU's subscription). You can sometimes find ebooks on these platforms that are not in Julius or Bobcat: