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“Artists' books are books made or conceived by artists. There are fine artists who make books and book artists who produce work exclusively in that medium, as well as illustrators, typographers, writers, poets, book binders, printers and many others who work collaboratively or alone to produce artists' books. Many artists' books are self-published, or are produced by small presses or by artists' groups or collectives, usually in limited editions.”--Victoria and Albert Museum, Artists' Books.
However, if the item doesn’t match the above, we will go by the artist intent: if an artist states that the item is an Artist’s Book, then it is an Artist’s Book.
“Even how to properly punctuate the term is disputed: whether ‘artist’s book,' ‘artists' book’ or ‘artist book.’”--Anne Evenhaugen, What is an artist’s book? (Unbound (Smithsonian), June 1, 2012).
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