APA   Click to copy
Liang, Z., Mao, J., Lu, K., & Li, G. (2021). Finding citations for PubMed: a large-scale comparison between five freely available bibliographic data sources. Scientometrics, 126, 9519–9542. https://doi.org/10.1007/s11192-021-04191-8

Chicago/Turabian   Click to copy
Liang, Zhentao, Jin Mao, Kun Lu, and Gang Li. “Finding Citations for PubMed: a Large-Scale Comparison between Five Freely Available Bibliographic Data Sources.” Scientometrics 126 (2021): 9519–9542.

MLA   Click to copy
Liang, Zhentao, et al. “Finding Citations for PubMed: a Large-Scale Comparison between Five Freely Available Bibliographic Data Sources.” Scientometrics, vol. 126, 2021, pp. 9519–42, doi:10.1007/s11192-021-04191-8.

@article{liang2021a,
  title = {Finding citations for PubMed: a large-scale comparison between five freely available bibliographic data sources},
  year = {2021},
  journal = {Scientometrics},
  pages = {9519--9542},
  volume = {126},
  doi = {10.1007/s11192-021-04191-8},
  author = {Liang, Zhentao and Mao, Jin and Lu, Kun and Li, Gang}
}