Individual-Level and Ecological Studies.

@article{Wills2018IndividualLevelAE,
  title={Individual-Level and Ecological Studies.},
  author={Thomas Ashby Wills and Samir S Soneji},
  journal={The Journal of adolescent health : official publication of the Society for Adolescent Medicine},
  year={2018},
  volume={62 5},
  pages={507-508}
}