Proof Theory,Basic proof theory 2nd edition | Programming languages and applied logic | Cambridge University Press,Proof Theory: Second Edition (Dover Books on Mathematics): Takeuti, Gaisi: 9780486490731: Amazon.com: Books,Basic Proof Theory (Cambridge Tracts in Theoretical Computer Science, Series Number 43): Troelstra, A. S., Schwichtenberg, H.: 9780521779111: Amazon.com: Books,combinatorics - A Question on a Proof for Erdos' Basic Sumfree Set Theorem (1965) - Mathematics Stack Exchange