A few days ago I was worried I wouldn't have enough sources to fill up my literature review. Now, I'm worried I'll have too many! In order to broaden my scope of sources, I consulted the bibliographies of my already-selected sources for helpful texts. I read a few interesting and relevant ones, which then led me to more studies of interest, and so on and so on. It was as if the floodgates had opened, and I couldn't stop the material from pouring in. This is the problem with research, especially research in a popular area: there's so much material! I couldn't possibly read every important content analysis study ever written, but with so many out there, I can't help but feel like if I don't look at them, I'll be missing something. Which is just a feeling I'm going to have to get used to, because in research, there's probably always going to be something you're not reading. I guess the important thing is to read as much as you can of the fundamental, cornerstone works that define your field so even if there is some new study on some small part related to yours, the foundation of your study will remain intact.
That is not to say that I've neglected my research, it's just that when using a popular method and studying in a broad field, it seems that widening your search parameters can be both useful and problematic. Too narrow and you've got nothing, too wide and you've got everything, and that is simply too much to go through in a few weeks.