Yubin Gao, Yihua Huang, Yanling Shao. Bases of primitive non-powerful signed symmetric digraphs with loops. Ars Comb., 90, 2009.
@article{GaoHS09, title = {Bases of primitive non-powerful signed symmetric digraphs with loops}, author = {Yubin Gao and Yihua Huang and Yanling Shao}, year = {2009}, researchr = {https://researchr.org/publication/GaoHS09}, cites = {0}, citedby = {0}, journal = {Ars Comb.}, volume = {90}, }