Ramsey, Frank Plumpton; "Truth and Probability" (PDFArchived 27 February 2008 at the Wayback Machine), Chapter VII in The Foundations of Mathematics and other Logical Essays (1931).
Bernoulli, Nicolas; letter of 5 April 1732, acknowledging receipt of "Specimen theoriae novae metiendi sortem pecuniariam" (excerpted in PDFArchived 9 September 2008 at the Wayback Machine).
Ramsey, Frank Plumpton; "Truth and Probability" (PDFArchived 27 February 2008 at the Wayback Machine), Chapter VII in The Foundations of Mathematics and other Logical Essays (1931).
Bernoulli, Nicolas; letter of 5 April 1732, acknowledging receipt of "Specimen theoriae novae metiendi sortem pecuniariam" (excerpted in PDFArchived 9 September 2008 at the Wayback Machine).