1. Y.T. Chen: Concrete Machinery (Building materials industry press, China 2002).
2. J.M. Yang: Journal of Construction Mechanization(1984), p.89.
3. J.M. Yang: Journal of Construction Mechanization(1984), p.91.
4. Z.J. Pei: Journal of Building Machinery(2007), p.32.
5. S.L. Cheng, L.L. Yao: Journal of Construction Mechanization(2002), p.15.