Eric C. Milner, Robert E. Woodrow. On directed graphs with an independent covering set. Graphs and Combinatorics, 5(1):363-369, 1989. [doi]
@article{MilnerW89,
title = {On directed graphs with an independent covering set},
author = {Eric C. Milner and Robert E. Woodrow},
year = {1989},
doi = {10.1007/BF01788692},
url = {http://dx.doi.org/10.1007/BF01788692},
researchr = {https://researchr.org/publication/MilnerW89},
cites = {0},
citedby = {0},
journal = {Graphs and Combinatorics},
volume = {5},
number = {1},
pages = {363-369},
}