Abeck, D, et al. “Atypical Presentation of Co-Existent Haemophilus Ducreyi and Treponema Pallidum Infection in an HIV-Positive Male”. Acta Dermato-Venereologica, vol. 72, no. 1, Jan. 1992, pp. 37-38, doi:10.2340/00015555723738.