Dean; Poulsen, Tina D.; Mikkelsen, Kurt V.; Ogilby, Peter R. Singlet Sigma: The "Other" Singlet Oxygen in Solution. Photochemistry and Photobiology. 1999
December 2016). Cox, Brian; Forshaw, Jeff; Lönnblad, Leif. Hard colour singlet exchange at the Tevatron. Journal of High Energy Physics. 1999, 1999 (10):