@Article{Bona97a,
    author = {C. Bona and J. Mass{\'o} and E. Seidel and J. Stela},
    title = {First order hyperbolic formalism for numerical relativity},
    journal = {Phys. Rev. D},
    year = {1997},
    volume = {56},
    pages = {3405-3415},
    note = {PHY94-07882,INT94-14185}
}