Garethfx's technique will work (I frequently use this method myself for dynamically updating rowsources for drop/list boxes in forms with a line of code to refresh the data.).
However, you did mention that you wanted a FIXED date range (assuming this really is an issue). If this is the case and you use that method you will then need to add code prevent the user from adding any range they want. Which is more work in the end. Also note that his method is for use in a FORM and if you plan to use this in a Query only you will get error messages as this type of query outside the context of a form will not know what the references to form fields are..