V. B. Meyer-Rochow, & J. Gal, Pressures produced when penguins pooh—calculations on avian defaecation. Polar Biology, vol. 27, no. 1, 2003, pp. 56-58.
J. T.Harvey, J. Culvenor, W. Payne, S. Cowley, M. Lawrance, D. Stuart, & R. Williams, R, An analysis of the forces required to drag sheep over various surfaces. Applied Ergonomics, vol. 33, no. 6, 2002, pp. 523-531.
R. E. Goldstein, P. B. Warren, & R. C. Ball, Shape of a ponytail and the statistical physics of hair fiber bundles. Physical Review Letters, vol. 108, no. 7, 2012, 078101
K. Mabuchi, K. Tanaka, D. Uchijima, & R. Sakai, Frictional coefficient under banana skin. Tribology Online, vol. 7, no. 3, 2012, pp. 147-151
H. Alarcón, T. Salez, C. Poulard, J. F. Bloch, É. Raphaël, K. Dalnoki-Veress, & F. Restagno, Self-amplification of solid friction in interleaved assemblies. Physical Review Letters, vol. 116, no. 1, 2016, 015502.