this study demonstrates relationships in envelope antigens of 4 human influenza a2 strains isolated during the period 1957-68 ( including a2/hong kong/68 ) , 2 strains of a/equi-2/63 and 7 avian influenza viruses isolated in europe , north america , and the ukraine in the years 1960-67 .
C0015176
europe
C0041580
ukraine