These chromaticity coordinates are related to the Stiles & Burch (1955) 2-deg CMFs by
where , , and are the chromaticity coordinates, and , and are the CMFs.
For more details refer to the Stiles & Burch 2 deg CMFs page.
Stiles, W. S. & Burch, J. M. (1955). Interim report to the Commission Internationale de l'Eclairage Zurich, 1955, on the National Physical Laboratory's investigation of colour-matching. Optica Acta, 2, 168-181.
Stiles, W. S. & Burch, J. M. (1959). NPL colour-matching investigation: Final report. Optica Acta, 6, 1-26.