Pearson’s output was vast: Morant’s bibliography lists 648 publications and some of the projects like the Elasticity and the Galton biography were on the grandest scale.
G. M. Morant (1939) A Bibliography of the Statistical and other Writings of Karl Pearson, Cambridge University Press.
For the statistical papers—at least—Morant provides abstracts and cross-references. Most of the abstracts were written by B. L. Welch.
Most of Pearson’s articles are now accessible through JSTOR. However many of his contributions to Biometrika were unsigned editorials and material from lectures and the only infallible method for finding them on JSTOR is to go through volume by volume. Alternatively use the Morant bibliography.
The Pearson Papers at University College London has more than 16,000 letters, family papers and scientific manuscripts, including students’ notes on Pearson’s lectures and the records of the Men and Women’s Club. A catalogue is available:
A list of the papers and correspondence of Karl Pearson (1857-1936) held in the Manuscripts Room, University College London Library compiled by M Merrington, B Blundell, S Burrough, J Golden, J Hogarth (University College London, 1983).
The AIM25 listing contains a basic description of the collection.
Porter (2004) has a long list of archives, the ones he used in writing his book. There is also material at King’s College, Cambridge (Bradshaw Papers), in the University Library at Cambridge, at the Royal Society, the Royal Astronomical Society, Adelaide University Library, the Worshipful Company of Drapers, the American Philosophical Society Library and the Rockefeller Archive Center.
