@article{NUMA_1993__65_4_133747,
     author = {Richard S. Varga and Reinhard Nabben},
     title = {An algorithm for determining if the inverse of a strictly diagonally dominant {Stieltjes} matrix is strictly ultrametric.},
     journal = {Numerische Mathematik},
     pages = {493--502},
     publisher = {mathdoc},
     volume = {65},
     number = {4},
     year = {1993},
     zbl = {0796.65029},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1993__65_4_133747/}
}