originally prepared under the direction of Karl Pearson ; with a new introduction by E.S. Pearson and N.L. JohnsonPublished for the Biometrika Trustees by Cambridge U.P.1968
by William Kingdon Clifford ; edited and with a preface by Karl Pearson ; newly edited and with an introduction by James R. Newman ; preface by Bertrand RussellDover Publications, Inc.1955