@Article{Pokorski:1998hr,
     author    = "Witold Pokorski and Graham G. Ross",
     title     = "Flat directions, string compactification and three
                  generation models",
     year      = "1998",
     eprint    = "hep-ph/9809537"
}
@Article{Ghilencea:1998st,
     author    = "Dumitru Ghilencea and Graham G. Ross",
     title     = "Unification and extra space-time dimensions",
     year      = "1998",
     eprint    = "hep-ph/9809217"
}
@Article{Amelino-Camelia:1998tm,
     author    = "G. Amelino-Camelia and Dumitru Ghilencea and Graham G. Ross
                  ",
     title     = "The Effect of Yukawa couplings on unification predictions
                  and the nonperturbative limit",
     journal   = "Nucl. Phys.",
     volume    = "B528",
     year      = "1998",
     pages     = "35",
     eprint    = "hep-ph/9804437"
}