TY - GEN T1 - Google Scholar, Web of Science, and Scopus: a systematic comparison of citations in 252 subject categories T2 - arXiv PY - 2018/08/15 AU - Martín-Martín A AU - Orduna-Malea E AU - Thelwall M AU - López-Cózar ED ED - DO - DOI: 10.48550/arxiv.1808.05053 Y2 - 2024/12/28 ER -