1. Physical Review;Kingsbury;A direct comparison of the loudness of pure tones,1927
2. Journal of the Acoustical Society of America;Fletcher;Loudness, its definition, measurement and calculation,1933
3. Journal of the Institution of Electrical Engineers;Churcher;The performance of noise meters in terms of the primary standard,1937
4. British Journal of Applied Physics;Robinson;A redetermination of the equal-loudness relations for pure tones,1956
5. ISO Recommendation R226;International Organization for Standardization, Geneva;Normal equal-loudness contours for pure tones and normal threshold of hearing under free-field listening conditions,1961