@article{ARM_1984_20_4_a1,
     author = {Kol\'a\v{r}, Ivan},
     title = {Natural transformations of the second tangent functor into itself},
     journal = {Archivum mathematicum},
     pages = {169--172},
     year = {1984},
     volume = {20},
     number = {4},
     mrnumber = {784868},
     zbl = {0578.58004},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/ARM_1984_20_4_a1/}
}