Articles to which the posted article follows up.
This property contains articles to which the posted article follows up. If this property contains a non-empty string, a References article header is created for the article. This header shows the article identifiers for the posted article to which it refers.
The references must be separated by space characters.
If the resulting header is longer than MaxHeaderLength, then it is folded according to RFC 850 specifications.
This property is not available at design time.