Correction to: The Double-Wedge Algebra for Quantum Fields on Schwarzschild and Minkowski Spacetimes

There is an error in the proof (but not the truth) of Theorem 3.2 in the author's 1985 paper "The Double-Wedge Algebra for Quantum Fields on Schwarzschild and Minkowski Spacetimes" in "Communications in Mathematical Physics". The author became aware of that error and of how it may be corrected soon after it went to print, and two companion papers published soon afterwards (in Helvetica Physica Acta) refer to an "erratum to appear". This is that erratum. We also take the opportunity to note a few (unrelated and minor) corrections to those two companion papers and also to very briefly mention related more recent work.