Level 1: Class T: Papers published in specialized journals refer to papers published in Science and Nature.

Level 2: Class A: authoritative core journal papers, referring to internationally accepted SCIE, el, ISTP, SSCI and A &；; Papers included in the HCI retrieval system (subject to the retrieval by China Institute of Science and Technology Information) or papers on the same topic published by authoritative Chinese core journals in China do not contain reportable abstracts, abstracts, news, etc.

Grade III: Class B: Important core journal papers, which refer to papers published in foreign core journals (see Handbook of Foreign Science and Technology Core Journals) or papers with important influence published in Chinese core journals of similar disciplines in China.

Level 4: Class C: general core periodical papers, which refer to the papers published in the magazine "Overview of National Chinese Core Periodicals | Peking University Library 2004 Edition".

Level 5: Class D: Papers published in general public journals refer to papers published in domestic public journals (journal number "CNSSN" with postal code).

Grade 6: Class E: Papers published in restricted public publications refer to papers published in domestic public publications with restricted distribution (only periodical number, no postal code).