@article{PIM_1991_N_S_49_63_a1,
     author = {Mirko Lepovi\'c},
     title = {On {Graphs} {Whose} {Energy} {Does} {Not} {Exceed} 4},
     journal = {Publications de l'Institut Math\'ematique},
     pages = {6 },
     publisher = {mathdoc},
     volume = {_N_S_49},
     number = {63},
     year = {1991},
     url = {http://geodesic.mathdoc.fr/item/PIM_1991_N_S_49_63_a1/}
}