1. Factual documents refer to documents that provide factual evidence for educational scientific research, including various forms and contents of factual materials that have been discovered and confirmed at home and abroad, such as various educational experiment reports and educational records of famous educators.

2. Instrumental literature refers to the literature that provides retrieval consultation for education and scientific research, including reference books, online retrieval queries, academic dynamic reviews, etc.

3. Theoretical literature refers to the literature that provides theoretical understanding for educational scientific research, including educational monographs, papers, collections, biographies of educators, methodological works, etc.

4. Policy documents refer to documents that provide policy basis for educational scientific research, including rules and regulations, government documents and statistical data.

5. Empirical documents refer to documents that provide perceptual knowledge for educational scientific research, including investigation reports, work summaries, experiences, educational reference books, teaching materials, teaching outlines, etc. of various schools at all levels.