RT Journal Article SR Electronic T1 Primary and secondary syphilis. Country of origin study, 1968. British Cooperative Clinical Group. JF The British Journal of Venereal Diseases JO Br J Vener Dis FD BMJ Publishing Group Ltd SP 69 OP 75 DO 10.1136/sti.46.1.69 VO 46 IS 1 YR 1970 UL http://sti.bmj.com/content/46/1/69.abstract AB