Canto, C. S.A., et al. “Nitrogen Removal in a Sequencing Batch Biofilm Reactor With Liquid Circulation: Effect of Feed Strategy and Carbonsource in the Denitrifying Step”. Afinidad. Journal of Chemical Engineering Theoretical and Applied Chemistry, vol. 67, no. 545, Oct. 2010, https://raco.cat/index.php/afinidad/article/view/269036.