Cundall, P. A., Sterling, R., Starfield, A. M., Sterling, R. L., & Starfield, A. M. (1988). Key questions in rock mechanics: Proceedings of the 29th U.S. Symposium, University of Minnesota, Minneapolis, 13-15 June 1988. Rotterdam ; Brookfield: Balkema.

Cundall, P. A., Raymond Sterling, A. M. Starfield, R. L. Sterling, and A. M. Starfield. Key Questions in Rock Mechanics: Proceedings of the 29th U.S. Symposium, University of Minnesota, Minneapolis, 13-15 June 1988. Rotterdam ; Brookfield: Balkema, 1988.

Cundall, P. A., et al. Key Questions in Rock Mechanics: Proceedings of the 29th U.S. Symposium, University of Minnesota, Minneapolis, 13-15 June 1988. Rotterdam ; Brookfield: Balkema, 1988.