A class of digraphs which have completely real Laplacian spectra(一类具有全实Laplacian谱的有向图) - SULi(苏莉); LIHong-hai(李红海) (Zhejiang Daxue xuebao. Lixue ban, 2011)
分别研究了一类带有Hamiltonian路和带有Hamiltonian圈的有向图的基本有圈性(essential cyclicity)，给出了这种有向图的Laplacian谱，表明这些图具有全实的Laplacian谱.