1. C. Zhou and Y. F. Yang: Acta Pratacul. Sin. Vol. 15 (2006), pp.76-81. (In Chinese).
2. L. Bo, Ecology(Higher Education Press, China 2000).
3. W. X. Fang and J. Yun: JPE. Vol. 32 (2008), pp.951-960. (In Chinese).
4. J. F. Gillooly and A. P. Allen: Biol. Lett. Val. 3 (2007), pp.99-102.
5. M. Makarieva, V. G. Gorshkov and B. Li: Theor. Biol. Val. 221 (2003), pp.301-307.