Rietveld, Piet, Jasper Dekkers, and Stefan van Woudenberg. “Choice of Frequency and Vehicle Size in Rail Transport: Implications for Marginal External Costs”. European Journal of Transport and Infrastructure Research 2, no. 2/3 (April 1, 2002). Accessed October 5, 2022. https://journals.open.tudelft.nl/ejtir/article/view/3691.