Introduction to Natural Language Understanding
Erwan Kina

Not a bad introduction. There’s a lot of ‘misguided’ hype about the state-of-the-art in NLU — especially with too much talk about chatbots, etc. Unfortunately, the currently predominant paradigm that is being used for NLU is inadequate (Statistical, Deep Learning, etc.). Language, unlike images and speech (which are data-centric problems where pattern recognition works), requires different approaches.
You might want to look at this

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