@article{AUCMP_2007__48_1_a6,
     author = {Fla\v{s}ka, V\'aclav and Jan\v{c}a\v{r}{\'\i}k, Anton{\'\i}n and Kala, V{\'\i}t\v{e}zslav and Kepka, Tom\'a\v{s}},
     title = {Trees in commtative nil-semigroups of index two},
     journal = {Acta Universitatis Carolinae. Mathematica et Physica},
     pages = {81--101},
     publisher = {mathdoc},
     volume = {48},
     number = {1},
     year = {2007},
     mrnumber = {2517611},
     zbl = {1169.20310},
     language = {en},
     url = {https://geodesic-test.mathdoc.fr/item/AUCMP_2007__48_1_a6/}
}