1. Y. Tanigawa, H. Mori: Cement & Concrete 501 (1988), p.11 (in Japanese).
2. Y. Tanigawa, H. Mori: Cement & Concrete 551 (1993), p.2 (in Japanese).
3. C.T. Kennedy: Journal of American Concrete Institute Vol. 36, No. 2 (1940), p.373.
4. T.C. Powers: The Properties of Fresh Concrete (John Wiley & Sons, Inc., New York 1968).
5. J. Miyake and H. Matsushita: Advance Concrete Technology Vol. 5, No. 1 ( 2007), p.87.