Voir la notice de l'article provenant de la source Czech Digital Mathematics Library
@article{UM_1997__5_3_a4, author = {Calda, Emil}, title = {Heron\r{u}v vzorec a kosinova v\v{e}ta}, journal = {U\v{c}itel matematiky}, pages = {157--159}, publisher = {mathdoc}, volume = {05}, number = {3}, year = {1997}, language = {cz}, url = {http://geodesic.mathdoc.fr/item/UM_1997__5_3_a4/} }
Calda, Emil. Heronův vzorec a kosinova věta. Učitel matematiky, Tome 05 (1997) no. 3, pp. 157-159. http://geodesic.mathdoc.fr/item/UM_1997__5_3_a4/