@article{DAm-Mar-Men-2018,
    author={Claudia d'Ambrosio and Silvano Martello and Luca Mencarelli },
    title={Relaxations and heuristics for the multiple non-linear 
           separable knapsack problem },
    doi={10.1016/j.cor.2017.12.017 },
    journal={Computers and Operations Research },
    year={2018 },
    month={5},
    volume={93 },
    pages={79--89},
}