@article{NUMA_1964__6_131600,
     author = {B.R. HEAP and M.S. LYNN},
     title = {The {Index} of {Primitivity} of a {Non-Negative} {Matrix.}},
     journal = {Numerische Mathematik},
     pages = {120--141},
     year = {1964},
     volume = {6},
     zbl = {0121.26303},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1964__6_131600/}
}