def title_intro_validate(root)
        title_intro_en = root.at("//title[@type='title-intro' and @language='en']")
        title_intro_zh = root.at("//title[@type='title-intro' and @language='zh']")
        if title_intro_en.nil? && !title_intro_zh.nil?
          @log.add("Style", title_intro_zh, "No English Title Intro!")