The National Library Reference Union failed to download, because the whole book could not be downloaded to protect copyright. Some books of National Library Reference Alliance are on trial, and basically 99% of them can be downloaded. In order to protect copyright, the government downloads some books through document delivery, but it cannot download the whole book at one time. There is also a kind of payment, which pays tens of dollars through third-party tools. The only bad thing is that they spend money on software, and each download costs a little more, but it is cheaper than letting others download it directly.