Spring Cleaning: How Long to Keep Textbooks?

Husband and I are participating in our seasonal ritual of cleaning out the old. We have consciously downsized  over the past two years, moving from a four bedroom house to much more humble digs in order to have time and resources for experiences versus things. 


As we move from room to room (bedroom and office are on the list for today), I come across old textbooks from graduate school. Most of my adult-centered materials are in my office at work, so these are primarily language development and disorders, articulation/ phonological disorders, audiology and fluency texts. I haven't needed to refer to them in about 3-4 years, but I feel like they are still great references. I do have limited storage space at home. I could pack them away in storage, but then I know I would never use them because, well, "out of sight, out of mind."

So, how long do you keep your old textbooks? Indefinitely? Some of these textbooks were actually given to me by other clinicians who either left the field or only worked with a certain population.