@article{AM2_1972__8_136288,
     author = {John David Logan},
     title = {Fist {Integrals} in the {Discrete} {Variational} {Calculus.} {(Short} {Communications).}},
     journal = {Aequationes mathematicae},
     pages = {199--200},
     year = {1972},
     volume = {8},
     url = {http://geodesic.mathdoc.fr/item/AM2_1972__8_136288/}
}