  We say that a cyclotomic polynomial \Phi_{n}(x) has order three if n is the
product of three distinct primes, p<q<r. Let A(n) be the largest absolute value
of a coefficient of \Phi_{n}(x) and M(p) be the maximum of A(pqr). In 1968,
Sister Marion Beiter conjectured that A(pqr)<=(p+1)/2. In 2008, Yves Gallot and
Pieter Moree showed that the conjecture is false for every p>=11, and they
proposed the Corrected Beiter conjecture: A(pqr)<=2p/3. Here we will give a
proof of this conjecture.
