TY  - RPRT
TI  - Derived variables for longitudinal studies.
AU  - D R Cox
AU  - N Wermuth
PY  - 1999
DO  - 10.1073/pnas.96.22.12273
UR  - https://pubmed.ncbi.nlm.nih.gov/10535911/
ID  - 10535911
ER  -