Barkell, J. F., D. O’Connor, and W. G. Cotton. “Situational Coupling at the Ruck and Its Effects on Phase Momentum and Success in International men’s and women’s Rugby Sevens”. Journal of Human Sport and Exercise, vol. 12, no. 2, July 2017, pp. 294-06, doi:10.14198/jhse.2017.122.06.