I have a small number of documents (I could probably get 4 or 5 documents) and want to assign terms in these documents a score based on its importance to the document. I want to find which terms are simultaneously important to all of these documents.
These documents have different authors but are written about the same topic, and I want to filter out keywords that are artifacts of the authors' writing styles.
TF-IDF seems like a well-established scoring function. However, the documents I have do not belong to a large corpus of documents, prohibiting the computation of IDF-values.
Q: How can I compute the TF-IDF score of terms within a handful of documents, but without my own corpus?
I'm open to alternative suggests that do not involve TF-IDF.