Google Scholar, Web of Science, and Scopus: A systematic comparison of citations in 252 subject categories

• Published in: Journal of informetrics Vol. 12; no. 4; pp. 1160 - 1177
• Main Authors: Martín-Martín, Alberto, Orduna-Malea, Enrique, Thelwall, Mike, Delgado López-Cózar, Emilio
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.11.2018
• Subjects: Academic search engines; Bibliographic databases; Bibliometrics; Citation analysis; Citation overlap; Coverage; Google Scholar; Scientometrics; Scopus; Unique citations; Web of Science; Web of Science; Unique citations; Scientometrics; Citation analysis; Bibliometrics; Scopus; Citation overlap; Bibliographic databases; Coverage; Academic search engines; Google Scholar

•Google Scholar found nearly all citations found by WoS (95%) and Scopus (92%), and a large amount of unique citations.•About half of Google Scholar unique citations are not from journals. A significant minority (19–38%) are not in English.•Google Scholar unique citations have, on average, a much lo...