1. 1) PIARC: Technical Committee Report on Surface Characteristics, 1978.
2. 2) ASTM: Standard Guide for Classification of Automated Pavement Condition Survey Equipment, Standard No. E1656-94.
3. 3) ASTM: Standard Guide for Conducting Subjective Payment Ride Quality Ratings, Standard No. E1927-98.
4. 4) Sayers, M. W. and T. D. Gillespie: The International Road Roughness Experiment: A Basis for Establising a Standard Scale for Road Roughness Measurements, Transportation Research Record, No. 1084, TRB, pp. 76-85, 1986.
5. 5) Sayers, M. W. and Gillespie, T. D.: The International Road Roughness Experiment, Establishing Correlation and a Calibration Standard for Measurements, No. HS-039-586, International Bank for Reconstruction and Development, 1986.