TY  - RPRT
TI  - Assessing perceived physical environmental variables that may influence physical activity.
AU  - J F Sallis
AU  - M F Johnson
AU  - K J Calfas
AU  - S Caparosa
AU  - J F Nichols
PY  - 1997
DO  - 10.1080/02701367.1997.10608015
UR  - https://pubmed.ncbi.nlm.nih.gov/9421846/
ID  - 9421846
ER  -