Given some natural language sentences like
I would like to talk to Mr. Smith
I would like to extract entities, like the person "Smith".
I know that frameworks, which are capable of doing so (f. e. RASA or spaCy), exist, but I would like to dive deeper and understand the theory behind all this.
At university, I learned a few of the basic models like CRF's or SVM's used for this task, but I wonder if there are any good resources (preferably books) about this topic.