  In the early years of NF studies (1937–1952) it was not known whether or not NF proved the axiom of infinity. Specker showed that it did, though he never published his proof: the (quite different) proof in Specker [1953] is of his stronger result that NF proves that the universe cannot be wellordered (and is therefore infinite) and the first published proof is in Henson [1973a])