digraph  aa{
  Series[label="Series 主题",shape="Mrecord"];
  eBook_Preview[label="电子书【预备】",shape="Mrecord"];
  eBook_Publish[label="电子书【发布】",shape="Mrecord"];
  eBook_Grown[label="电子书【稳定】",shape="Mrecord"];

  Series -> eBook_Preview -> eBook_Publish -> eBook_Grown;
}