1, SCI (scientific citation index) was founded by institute for scientific information, USA. It contains the author, title and keywords of the literature, which can not only evaluate the academic value of the article from the perspective of literature citation, but also establish a reference network for research topics quickly and conveniently. SCI was established in 196 1. After 40 years of development and improvement, it has developed from a single printing type to a powerful electronic, integrated and networked large-scale multidisciplinary comprehensive retrieval system.

2. SSCI (Social Science Citation Index), also founded by institute for scientific information, is a large-scale retrieval tool, which can be used to analyze the number of social science papers in different countries and regions.

3.EI (Engineering Index), founded in 1884, is a famous comprehensive retrieval tool for engineering technology published by American Engineering Information Company. Each issue is accompanied by a subject index and an author index; There is also an annual volume and an annual index every year, and the annual index also increases the author unit index. There are print (periodicals), electronic (tapes) and microfilm.

4.ISTP (Index of Science and Technology Conference Proceedings), founded in 1978, edited and published by institute for scientific information, USA. In international academic exchanges, academic conference documents are very important original documents. New theories, new signs and new ideas are often first announced at academic conferences and published in the form of conference proceedings.