Christofi, N., Aspichueta, E., Dalzell, D., De la Sota, A., Etxebarria, J., Fernandes, T., Gutierrez, M., Morton, J., Obst, U., & Schmellenkamp, P. (2003). Congruence in the performance of model nitrifying activated sludge plants located in Germany, Scotland and Spain. Water Research, 37(1), 177-187. https://doi.org/10.1016/s0043-1354%2802%2900119-7