1. Drilling for Energy Resources;Committee on Technology of Drilling for Energy Resources,1976
2. History of Oil Well Drilling;Brantly,1971
3. Rotary drilling holes in coalbeds for degasification;Cervik;U.S. Bureau of Mines Report of Investigations 8097,1975
4. Horizontal drilling technology for advance degasification;Thakur;Min. Engng.,1980
5. The development of a round-the-corner drill;Barker,1979