public override string ToString()
{
if (Inlines == null || Url == null)
return base.ToString();
if (ReferenceId != null)
return string.Format("[{0}][{1}]", string.Join(string.Empty, Inlines), ReferenceId);
return string.Format("[{0}]({1})", string.Join(string.Empty, Inlines), Url);
}