@article{Egger1997,
author = {Egger, M. and Smith, G.D. and Schneider, M. and Minder, C.},
title= {Bias in meta-analysis detected by a simple, graphical test},
year = {1997},
doi = {10.1136/bmj.315.7109.629},
volume = {315},
number = {7129},
pages = {629--634},
}