Latest version:
Oracle Database 19c
Older version, still maintained:
Oracle Database 18c,Oracle Database 12c Release 2
Old version:
Oracle Database 12c Release 1,Oracle Database 11g Release 2,Oracle Database 11g Release 1,Oracle Database 10g Release 2,Oracle Database 10g Release 1,Oracle9i Database Release 2,Oracle9i Database,Oracle8i Database,Oracle8 Database,Oracle 7.3,Oracle 7.2,Oracle 7.1,Oracle7,Oracle 6.2,Oracle v6,Oracle v5,Oracle v4,Oracle v3,Oracle v2