@article{CRMATH_2006__342_12_909_0,
     author = {Chill, Ralph and Fa\v{s}angov\'a, Eva and Metafune, Giorgio and Pallara, Diego},
     title = {The sector of analyticity of nonsymmetric submarkovian semigroups generated by elliptic operators},
     journal = {Comptes Rendus. Math\'ematique},
     pages = {909--914},
     publisher = {Elsevier},
     volume = {342},
     number = {12},
     year = {2006},
     doi = {10.1016/j.crma.2006.04.003},
     language = {en},
     url = {http://archive.numdam.org/articles/10.1016/j.crma.2006.04.003/}
}