The Wayback Machine - https://web.archive.org/web/20220320031912/https://bbs.pku.edu.cn/attach/0c/51/0c5149ff10a492f1/%E6%B5%B7%E5%8D%97%E7%9C%81%E4%BA%BA%E6%B0%91%E6%94%BF%E5%BA%9C%E5%8A%9E%E5%85%AC%E5%8E%85%E5%85%B3%E4%BA%8E%E5%8D%B0%E5%8F%91%E6%8F%90%E5%8D%87%E6%B5%B7%E5%8D%97%E6%97%85%E6%B8%B8%E5%9B%BD%E9%99%85%E5%8C%96%E6%B0%B4%E5%B9%B3.pdf