@article{AMI_2017_47_a1,
     author = {Jan Caha and Ji\v{r}{\'\i} Dvorsk\'y},
     title = {First derivatives of fuzzy surfaces},
     journal = {Annales mathematicae et informaticae},
     pages = {19--40},
     publisher = {mathdoc},
     volume = {47},
     year = {2017},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/AMI_2017_47_a1/}
}