ENCOG

http://www.heatonresearch.com/encog/

https://github.com/encog/encog-dotnet-core

https://github.com/encog/encog-sample-csharp

http://www.codeproject.com/Articles/54575/An-Introduction-to-Encog-Neural-Networks-for-C

Books:

https://s3.amazonaws.com/heatonresearch-books/free/encog-3_3-quickstart.pdf