References specification

REFERENCES table-Name [ ( Simple-column-Name [ , Simple-column-Name ]* ) ]
[ ON DELETE {NO ACTION | RESTRICT | CASCADE | SET NULL}]
   [ ON UPDATE {NO ACTION | RESTRICT }]
|
[ ON UPDATE {NO ACTION | RESTRICT }] [ ON DELETE
   {NO ACTION | RESTRICT | CASCADE | SET NULL}] 
Related reference
Column-level-constraint
Table-level constraint
searchCondition