These marketing books are great resources for students, researchers, or anyone interested in the field of marketing. To use them, simply open up the pages and start reading to gain valuable insights. When handling the books, be gentle as they are old and might have some wear. To maintain them, keep them in a dry and cool place away from direct sunlight. Avoid eating or drinking near them to prevent spills. If you need to take notes, use a bookmark or a piece of paper instead of writing directly in the books, especially considering the existing markings from previous owners.