Give them to a Charity shop. Rather than have an MSE "moral dilemma" . Help your local hospice which has probably struggled with fund raising throughout the pandemic.
Check your contract? That should tell you if the books were expected to be returned.
I'd sell them, if I could. Giving them to a charity shop, if they are specialised books, will be a waste of time because nobody wants to buy that kind of book from charities.
For over 45 shows in January and February
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