@inproceedings{longitudinaldataanalysisusinggeneralized,
  title = {Longitudinal data analysis using generalized linear models},
  author = {KUNG-YEE LIANG and Scott L. Zeger},
  year = {1986},
  booktitle = {Biometrika 1986 4},
  url = {https://doi.org/10.1093/biomet/73.1.13},
}