Twenty-one Shakespearean plays, published as quartos, can be seen in that form on the Web, courtesy the British Library.
Different versions appeared of the same work. In Hamlet, Act 3, Scene 1, a “bad” quarto published in 1603 said: “To be, or not to be, I there’s the point.” Two years later a “good” quarto said: “To be, or not to be, that is the question.” Whew!
You can compare the two versions.
(Spotted via Reuters.)
