下面这个 blockquote 元素中的 cite 属性指定了引用的来源 - 在线编辑器

          < blockquote cite = "http://www.worldwildlife.org/who/index.html" >
  For 50 years, WWF has been protecting the future of nature.The world 's
leading conservation organization, WWF works in 100 countries and is
supported by 1.2 million members in the United States and close to 5 million
globally.WWF 's unique way of working combines global reach with a
foundation in science, involves action at every level from local to global,
  and ensures the delivery of innovative solutions that meet the needs of both
people and nature. <
  /blockquote>
        