“What not to buy” is an academic study that resulted from a short sabbatical. Since many books in academic libraries are never used, I wanted to see if those books shared characteristics that buyers could keep an eye out for and only purchase carefully, saving money and shelf space. The short version is that books that were added to small holdings in a Library of Congress classification, and books from university or academic presses were unlikely to ever receive use. The article can be read at What Not to Buy: How to Identify Books Likely to be Unused Before Purchase.