@article {IOPORT.50280986,
    author       = {Lerman, Isra\"el-C\'esar and Kuntz, Pascale},
    title        = {Directed binary hierarchies and directed ultrametrics},
    year         = {2011},
    journal      = {J. Classification},
    volume       = {28},
    number       = {3},
    pages        = {272-296},
    doi          = {10.1007/s00357-011-9091-y},
    identifier   = {50280986},
}