1. Library: Go to the school or public library and use the resources of the library for document retrieval. In the library, you can find relevant literature through book catalogue, book retrieval system and periodical database.

2. Academic search engines: Use academic search engines, such as Google Academic, Baidu Academic and Wanfang. , and enter keywords to get the search results of related documents.

3. Academic journal websites: Go to the official websites of academic journals, such as ScienceDirect, Springer, Wiley online library, etc. Used for literature retrieval.

4. Proceedings of academic conference: Go to the academic conference in official website, find relevant conference proceedings and obtain relevant documents.

5. Professional databases: Go to professional databases, such as CNKI, Web of Science, Scopus, etc. , used for literature retrieval.

When looking for literature, you need to pay attention to the following points:

1. Keyword selection: Choosing appropriate keywords can improve the accuracy and efficiency of document retrieval.

2. Retrieval strategy: According to different needs, different retrieval strategies are adopted, such as accurate retrieval, fuzzy retrieval and combination retrieval.

3. Document quality: Selecting high-quality documents can improve the credibility and scientific value of research.

4. Cite documents: After finding relevant documents, record and quote them in time to avoid omission and plagiarism.