@article{MO_2021_97_1_a0,
     author = {V. K. Gavrilov},
     title = {From equality of {Pythagoras} to equality of {Ptolemy}},
     journal = {Matemati\v{c}eskoe obrazovanie},
     pages = {2--4},
     publisher = {mathdoc},
     volume = {97},
     number = {1},
     year = {2021},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MO_2021_97_1_a0/}
}