@article{JEMS_2006_8_2_a5,
     author = {Henri Berestycki and Luca Rossi},
     title = {On the principal eigenvalue of elliptic operators in $\R^N$ and applications},
     journal = {Journal of the European Mathematical Society},
     pages = {195--215},
     publisher = {mathdoc},
     volume = {8},
     number = {2},
     year = {2006},
     doi = {10.4171/jems/47},
     url = {http://geodesic.mathdoc.fr/articles/10.4171/jems/47/}
}