ei has three kinds of source journals, namely, selected journals, selected journals and extended journals. Among them,

all selected journals (core journals): all journals are entered into Compendex, and chemical engineering, civil engineering, electrical and electronic engineering, mechanical engineering, metallurgy, mining, petroleum engineering, computer engineering and software are selected as journals: some journals are entered into Compendex. Extended journals such as agricultural engineering, industrial engineering, textile engineering, applied chemistry, applied mathematics, applied mechanics, atmospheric science, papermaking chemistry and technology, engineering journals of colleges and universities, etc.: EI Page One

(2)Compendex data: The data is comprehensive, mainly including: the Title)； of the paper; Authors; First author affiliation; English abstract; Serial title)； of the journal where the paper is located; Volume issue; Pages)； of papers; Classification code (EI Classification Codes); Keyword (ei main heading); Ei controlled terms; Uncontrolled terms and so on. In which: classification code; Keyword (ei main heading); Ei controlled terms; Uncontrolled terms need to be given by professionals alone.

Page One data: the data mainly includes: the Title)； of the paper; Authors; Serial title)； of the journal where the paper is located; Volume issue; Pages)； of papers; Some data have English abstracts and First author affiliation. There is no need for any professionals to do any more work. The main differences between Compendex data and Page One data are: whether there are classification code and heading in the data; The data with these two contents is Compendex data, and vice versa.