I am working on weeding my biography section and thought I'd crowd source my question. My biography section sits neatly on the shelf, relatively untouched for the past 5 years. It contains different level readability books on the same person. As these are not read, and biographies are readily available online, my desire is to weed down based on year published and last circulation. Does anyone have thoughts on why I should keep multiple reading levels of these biographies?