@article{KJM_2003_25_1_a21,
     author = {Emilija Ne\v{s}ovi\'c and Miroslava Petrovi\'c-Torga\v{s}ev},
     title = {Some trigonometric relations in the {Lorentzian} plane},
     journal = {Kragujevac Journal of Mathematics},
     pages = {219 - 225},
     publisher = {mathdoc},
     volume = {25},
     number = {1},
     year = {2003},
     url = {http://geodesic.mathdoc.fr/item/KJM_2003_25_1_a21/}
}