Kamaku, Waweru, Josephine Mutembei, and Benard Kivunge. 2017. “Positive P 0,1 Matrix Completion Problem for Order Four Digraphs With Zero, One, Two and Three Arcs”. International Journal of Sciences: Basic and Applied Research (IJSBAR) 34 (3): 22-30. https://www.gssrr.org/JournalOfBasicAndApplied/article/view/7671.