1. ANON, 1976: Reclamation of Derelict Land: Procedure for Locating Abandoned Mine Shafts. Department of the Environment, London.
2. ANON, 1981a. Code of Practice for Site Investigations, BS5930. British Standards Institution, London.
3. ANON, 1981b: Code of Safe Drilling Practice. Part I, Surface Drilling. British Drilling Association, London.
4. ANON, 1982: Treatment of Disused Mine Shafts and Adits. National Coal Board, London.
5. BALLARD R. F., CUENOD, Y. and JENNI J.P., 1983: Detection of Karst Cavities by Geophysical Methods. Bulletin of the International Association of Engineering Geology, No. 26-27, pp. 153–157.