@article{10_37236_1444,
     author = {Fan Chung and S.-T. Yau},
     title = {Coverings, heat kernels and spanning trees},
     journal = {The electronic journal of combinatorics},
     year = {1999},
     volume = {6},
     doi = {10.37236/1444},
     zbl = {0915.05084},
     url = {http://geodesic.mathdoc.fr/articles/10.37236/1444/}
}