  New, doubling proofs are given for the interior Hessian estimates of the
special Lagrangian equation. These estimates were originally shown by
Chen-Warren-Yuan in CPAM 2009 and Wang-Yuan in AJM 2014. This yields a higher
codimension analogue of Korevaar's 1987 pointwise proof of the gradient
estimate for minimal hypersurfaces, without using the Michael-Simon mean value
inequality.
