RT Journal Article SR Electronic T1 Primary and secondary syphilis. Country of origin study, 1969. British Cooperative Clinical Group. JF The British Journal of Venereal Diseases JO Br J Vener Dis FD BMJ Publishing Group Ltd SP 477 OP 484 DO 10.1136/sti.46.6.477 VO 46 IS 6 YR 1970 UL http://sti.bmj.com/content/46/6/477.abstract AB