@article{JGG_2008_12_1_JGG_2008_12_1_a2,
     author = {C. Kimberling },
     title = {Yff {Conics}},
     journal = {Journal for geometry and graphics},
     pages = {23--34},
     publisher = {mathdoc},
     volume = {12},
     number = {1},
     year = {2008},
     url = {http://geodesic.mathdoc.fr/item/JGG_2008_12_1_JGG_2008_12_1_a2/}
}