The short answer to this is ‘no’, you are not supposed to do this. In a worst case scenario, your marker might think you are trying to create the impression that you have read more books and articles than you actually have, and that you are artificially inflating your bibliography. However, I trust you! That’s probably not what you are doing. Rather, I am assuming you have read these texts and they have informed your thinking on the topic, but it was more in a general way. You really want to give them due credit, you just did not find anything specifically citation-worthy in them. If this is the case, keep reading. This blogpost makes some quick and easy suggestions for solving this dilemma.