@article{SF_1992__45_3_135175,
     author = {M.G. Ulmet},
     title = {Boundary conditions for one-dimensional   positive semigroups.},
     journal = {Semigroup forum},
     pages = {92--119},
     publisher = {mathdoc},
     volume = {45},
     number = {3},
     year = {1992},
     zbl = {0778.47033},
     url = {http://geodesic.mathdoc.fr/item/SF_1992__45_3_135175/}
}