TY  - JOUR 
T1  - Observational studies: why are they so
               important?
JO  - Sao Paulo Medical Journal
A1  - Mariani, Alessandro Wasum
A1  - Pêgo-Fernandes, Paulo Manuel
SN  - 1516-3180
UL  - 10.1590/1516-3180.2014.1321784
VL  - 132 
Y1  - 2014
PB  - Brasil 
ER  -