ffnet was created in the hope that it will be useful. If you think it really is useful and you are going to publish some ffnet generated results, please cite one of (or all of them):

Marek Wojciechowski, Application of artificial neural network in soil parameter identification for deep excavation numerical model, Computer Assisted Mechanics and Engineering Sciences, 18(4): 303-311, 2011

Marek Wojciechowski, Solving differential equations by means of feed-forward artificial neural networks, Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
7267(1): 187-195, 2012

Marek Wojciechowski, Feed-forward neural network for python, Technical University of Łódź,, 2005-2016, Łódź, Poland

You can also look at the growing list of publications which use (and cite) ffnet.