Literature can be challenging to research because there simply is not as much written about it as many other subjects. Here are some more things that can be challenging when researching literature:
It is easier to find criticism on authors from the past than on contemporary authors. They have not been around as long to study or have had sufficient if any critical articles written about them. There can be exceptions to this.
Authors who are women or minorities from any era have had less written about their works, though that is changing. There just may be less available
There are some works about which there is not much written, even some works by the most famous authors.
Use COM Library's databases to get the college level articles you need for your research faster.