First, Chinese and foreign academic journals in the library, after finding one or two "classic" articles, "follow the trail" and pay attention to their references. High-quality academic articles usually do not ignore the mainstream and classic literature in this field.

Secondly, we can find some early classic documents by using China periodical network, foreign periodical database retrieval and foreign back issue reading room of school library.

Third, the national library. Some social science books published in the 1970s and 1980s or even earlier are often not collected by school libraries, but there are quite a few national maps (all books published in China must be submitted to the National Library). In addition, the national map also contains many foreign books about China's politics and government, which can be easily found on the Internet.

A journey of a thousand miles begins with a single step, and the writing of papers and documents is a long process that accumulates over time. For particularly important documents, you might as well make a reading note and extract important points and arguments. In this way, one step at a time, when I really started writing my thesis, I accumulated a lot of "dry goods" that I could enjoy at any time.