@article{ARM_1980__16_4_a1,
     author = {Barv{\'\i}nek, Erich},
     title = {Linear differential transformations of the 2nd order as a representation of an abstract model},
     journal = {Archivum mathematicum},
     pages = {189--198},
     publisher = {mathdoc},
     volume = {16},
     number = {4},
     year = {1980},
     mrnumber = {594465},
     zbl = {0465.34005},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/ARM_1980__16_4_a1/}
}