1. Tong J, Ren L, Chen B. Geometrical Morphology, Chemical Constitution and Wetability of Body Surfaces of Soil Animals. International Agricultural Engineering Journal, 1994, 3(1, 2): 59–68.
2. Ren L, Chen D, Hu J. Initial Analysis on the Law of Reducing Adhesion of Soil Animals. Transactions of the Chinese Society of Agricultural Machinery, 1990, 21(1): 15–20.
3. Li Jian-qiao, Sun Jiu-rong, Ren Lu-quan, Chen Bing-cong. Sliding Resistance of Plates with Bionic Bumpy Surface Against-soil. Journal of Bionics Engineering, 2004, 1(4): 207–214.
4. Sun Jiu-rong, Li Jian-qiao, Cheng Hong, Dai Zhen-dong, Ren Lu-quan. Restudies on Body Surface of Dung Beetle and Application of its Bionics Flexible Technique. Journal of Bionics Engineering, 2004, 1(1): 53–60.
5. Cong Q, Ren L, Wu L, Chen B. Taxonomic Research on Geometric Non-smooth Animal Surface Shapes. Transactions of the Chinese Society of Agricultural Engineering, 1992, 8(2): 7–12.