Philip T. Broughton and  Mark P. Bettney and  Isla L. Smail,  Field Trial of Resin-Based Composite Materials for the Treatment of Surface Collapses Associated with Former Shallow Coal Mining.   journal   = {International Journal of Geological and Environmental Engineering}, [online]. World Academy of Science, Engineering and Technology.
    January 2016, vol. 110(2). 186 - 190
    [viewed 22 January 2020]. Available from: https://publications.waset.org/pdf/10003690.