G. Jamshid and E. R. Randall, “Interaction between Two Parallel Tunnels,” International Journal for Numerical and Analytical Methods in Geomechanics, Vol. 1, No. 1, 1977, pp. 75-103.
 J. Wang, D. Milne, L. Wegner and M. Reeves, “Numerical Evaluation of the Effects of Stress and Excavation Surface Geometry on the Zone of Relaxation around Open Stope Hanging Walls,” International Journal of Rock Mechanics & Mining Sciences, Vol. 44, No. 2, 2007, pp. 289-298.
 Mathews, K. E. Hoek, D. C. Wyllie and S. B. V. Stewart, “Prediction Of Stable Excavation Spans for Mining at Depths below 1000 Metres in Hard Rock,” Report to Canada Centre for Mining and Energy Tehnology, 1980.