Counterexamples to an edge spread question for zero forcing number

GERARD JENNHWA CHANG2018-09-102018-09-102014http://www.scopus.com/inward/record.url?eid=2-s2.0-84894226125&partnerID=MN8TOARShttp://scholars.lib.ntu.edu.tw/handle/123456789/384400Counterexamples to an edge spread question for zero forcing numberjournal article10.1016/j.laa.2014.01.009