Elloumi, N., Belhaj, D., Jerbi, B., Zouari, M. and Kallel, M. 2017. Effects of sewage sludge on bio-accumulation of heavy metals in tomato seedlings. Spanish Journal of Agricultural Research. 14, 4 (Jan. 2017), e0807. DOI:https://doi.org/10.5424/sjar/2016144-9210.