@article{ELMA_1987__42_4_141415,
     author = {George A. Tsintsifas},
     title = {A generalization of a two triangle inequality.},
     journal = {Elemente der Mathematik},
     pages = {150--153},
     publisher = {mathdoc},
     volume = {42},
     number = {4},
     year = {1987},
     zbl = {0714.51013},
     url = {http://geodesic.mathdoc.fr/item/ELMA_1987__42_4_141415/}
}