@article{PIM_1977_N_S_21_35_a12,
     author = {Ivan Gutman},
     title = {Generalizations {Of} {A} {Reccurence} {Relation} {For} {The} {Characteristic} {Polynomials} {Of} {Trees}},
     journal = {Publications de l'Institut Math\'ematique},
     pages = {75 },
     publisher = {mathdoc},
     volume = {_N_S_21},
     number = {35},
     year = {1977},
     url = {http://geodesic.mathdoc.fr/item/PIM_1977_N_S_21_35_a12/}
}