Having a tidy up - what should I do with these books

[#1]

User's Guide and Reference MS- DOS Operating System version 5.0
User's Guide Microsoft Windows Version 3.1
Serious suggestions only please or some interfering mod will move this to Chit Chat 
Also but not really Windows related
Program Library Casio FX-720P and FX-820P
Owners Manual FX-4500P
and I have no idea why I have these as the calculators went to the tip years ago

[#2]

Stick them on your local Freegle or Freecycle and someone will bite your hand off for them.

[#3]

Pity they aren`t first editions ! ! ... could be worth quite a bit in 50 years time....