Law of contract

Hello Mike
I have a bit of a doubt.. Say for example I want to sell old books..On one of the selling website I added list of the book with the price details and other description. I was contacted by a person about the book and I agreed.. So the contract is established but i forgot to take it off from the website. Later another person wrote to me that he accepts the offer and wants to buy a book but the book is already sold to someone else.. Can the person sue me for breach of contract ?
Many thanks in advance