Strohmaier, K. G., P. M. Cronk, and J. D. Van de Ven. “Design Optimization of a Hydraulic Flywheel Accumulator for a Hydraulic Hybrid Vehicle”. International Journal of Fluid Power, vol. 16, no. 3, Nov. 2015, pp. 149-61, doi:10.1080/14399776.2015.1103102.