Link

Nelson, P.P., Peterson, C.R., Einstein, H.H., and Hood, M. (1992). Manufacturing underground space. In: Proceedings of international congress Towards New Worlds in Tunneling / Hacia Nuevos Mundos en Tuneles (L. Vieitez-Utesa, ed.), vol.1, Acapulco, Mexico, pp. 29-36. Published by CRC Press, 1992. ISBN 978-9054100515