@article{VM_2011_13_1_a1,
     author = {J. Scott Carter and David Mullens},
     title = {Heron's {Formula} from a {4-Dimensional} {Perspective}},
     journal = {Visual Mathematics},
     publisher = {mathdoc},
     volume = {13},
     number = {1},
     year = {2011},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/VM_2011_13_1_a1/}
}