@misc{indiciaeb26377027226,
  title = {Trends and natural variability of North American spring onset as evaluated by a new gridded dataset of spring indices},
  author = {Toby R. Ault and Mark D. Schwartz and Raul Zurita-Milla and Jake F. Weltzin and Julio L. Betancourt},
  year = {2015},
  doi = {10.1175/jcli-d-14-00736.1},
  url = {https://pubs.usgs.gov/publication/70186185},
  note = {Source identifier: 70186185}
}