Satya Prakash Pranav Kumar B. V. N. S. Prasad Anuj Gupta Pareto optimal solutions of a cost-time trade-off bulk transportation problem. 85-100 2008 188 European Journal of Operational Research 1 http://dx.doi.org/10.1016/j.ejor.2007.03.040 db/journals/eor/eor188.html#PrakashKPG08