@article{ZR_2011_14_22_a4,
     author = {Ivan Gutman},
     title = {Hyperenergetic and {Hypoenergetic} {Graphs}},
     journal = {Zbornik radova},
     pages = {113 },
     publisher = {mathdoc},
     volume = {14},
     number = {22},
     year = {2011},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/ZR_2011_14_22_a4/}
}