@article{JGG_2018_22_1_JGG_2018_22_1_a2,
     author = {N. Anghel },
     title = {Concurrency in {Hexagons} -- {A} {Trigonometric} {Tale}},
     journal = {Journal for geometry and graphics},
     pages = {21--29},
     publisher = {mathdoc},
     volume = {22},
     number = {1},
     year = {2018},
     url = {http://geodesic.mathdoc.fr/item/JGG_2018_22_1_JGG_2018_22_1_a2/}
}