1. Library: The library is one of the main ways to obtain academic literature. University libraries usually have rich academic databases and paper periodicals, which can provide a large number of academic resources. Students can inquire and borrow books through the library website or in person.

2. Academic database: Academic database is an online platform for collecting academic resources such as academic journals, conference papers and dissertations. Common academic databases include WebofScience, Scopus, PubMed, IEEEXplore, etc. These databases provide literature retrieval functions in a wide range of disciplines and time ranges.

3. Academic search engine: An academic search engine is a search tool that integrates multiple academic databases and academic resources. Common academic search engines include GoogleScholar, Baidu Academic, CNKI, etc. Users can search by inputting information such as keywords or authors, and the search engine will return relevant academic literature links.

4. Professional forums and social media: Some professional forums and social media platforms also have many scholars and researchers sharing their research results and literature resources. For example, ResearchGate is a social networking platform for researchers, where users can publish papers, discuss problems and share resources.

5. Tutor and peer recommendation: Tutors and peers are important channels for obtaining academic documents. They usually have rich research experience and literature resources, and can recommend some important academic literature to students.

In short, there are many ways to retrieve papers and documents, and students can choose the appropriate method to retrieve documents according to their own needs and conditions.