美国国家学术出版社 The National Academies Press出版的大部分PDF版图书对所有读者免费开放下载，并且将这些图书去除DRM保护 The National Academies Press (NAP) publishes authoritative reports issued by The National Academies of Science, Engineering, and Medicine (NASEM).0530书籍论文共享资源# agriculture# behavioral social sciences# biology
地球的演化时间表 Timeline of Earth Timeline of Earth - An interactive timline of the history of Earth by @Dubly0890创意生成创意生成器# andy bergmann# Data# dinosaurs
