@article{ZR_2011_14_22_a6,
     author = {Ivan Gutman and Hanyuan Deng and Slavko Radenkovi\'c},
     title = {The {Estrada} {Index:} {An} {Updated} {Survey}},
     journal = {Zbornik radova},
     pages = {155 },
     publisher = {mathdoc},
     volume = {14},
     number = {22},
     year = {2011},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/ZR_2011_14_22_a6/}
}