1. Araghi MS, Samani FB, Goudarzi MT (2006) A proposal for the modification of RQD (MRQD). In: Proceeding of 4th Asian rock mechanics symposium, rock mechanics in underground construction. ISRM International Symposium
2. Azimian A (2016) A new method for improving the RQD determination of rock core in borehole. Rock Mech Rock Eng 49(4):1559–1566
3. Bieniawski ZT (1989) Engineering rock mass classification: a complete manual for engineers and geologists in mining, civil, and petroleum engineering. Wiley, New York, p 251
4. Chen JP, Fan JH, Liu D (2005) Review and prospect on the application and research of RQD. Rock Soil Mech 26(S.2):249–252 (in Chinese)
5. Choi SY, Park HD (2004) Variation of rock quality designation (RQD) with scanline orientation and length: a case study in Korea. Int J Rock Mech Min Sci 41(2):207–221