RT Journal Article SR Electronic(1) A1 Reid, F YR 2001 T1 Bulgaria’s response to cases of poliomyelitis caused by imported wild poliovirus JF Weekly releases (1997–2007) VO 5 IS 45 SP 2052 OP DO https://doi.org/10.2807/esw.05.45.02052-en UL https://www.eurosurveillance.org/content/10.2807/esw.05.45.02052-en