Tomno V, Nyamwala F, Kamaku W. The Wss P0 Matrix Completion Problem for Symmetric Patterns of Acyclic Digraphs of Order Four. IJSBAR. 2018;37(1):112-121. Accessed April 3, 2026. https://www.gssrr.org/JournalOfBasicAndApplied/article/view/8591