TY  - RPRT
TI  - Birds return every spring like clockwork, but where is the clock?
AU  - Gregory F Ball
AU  - Jacques Balthazart
PY  - 2003
DO  - 10.1210/en.2003-0781
UR  - https://pubmed.ncbi.nlm.nih.gov/12933642/
ID  - 12933642
ER  -