Journal Article Computing the distribution of quadratic forms in normal variables Get access J. P. IMHOF J. P. IMHOF University of Geneva Search for other works by this author on: Oxford Academic Google Scholar Biometrika, Volume 48, Issue 3-4, December 1961, Pages 419–426, https://doi.org/10.1093/biomet/48.3-4.419 Published: 01 December 1961
J. P. Imhof (Sun,) studied this question.