Veugelers PJ , Fisk JD, Brown MG, et al. Disease progression among multiple sclerosis patients before and during a disease-modifying drug program: A longitudinal population-based evaluation. Mult Scler2009 ; 15: 1286-1294.
2.
Weinshenker BG, Bass B., Rice GPA, et al. The natural history of multiple sclerosis: A geographically based study. Brain1991; 114: 1057-1067.