García Heras, M., J. M. Rincoón López, A. Jimeno Martínez, and M. A. Villegas Broncano. “Archaeometric Study of Glass Beads from the 2nd Century BC Cemetery of Numantia”. Trabajos De Prehistoria, vol. 60, no. 1, June 2003, pp. 173-81, doi:10.3989/tp.2003.v60.i1.129.