TY  - RPRT
TI  - Spring onset variations and trends in the continental United States: past and regional assessment using temperature-based indices
AU  - Mark D. Schwartz
AU  - Toby R. Ault
AU  - Julio L. Betancourt
PY  - 2012
DO  - 10.1002/joc.3625
UR  - https://pubs.usgs.gov/publication/70039016
ID  - 70039016
ER  -