1. A method, comprising: electronically receiving, by a computer-implemented natural language processor, a natural language input phrase from an interface device; attributing, by the natural language processor, a concept to the phrase; searching a database, by the natural language processor, for a set of documents to identify one or more documents associated with the attributed concept to be included in a response to the natural language input phrase; maintaining, by the natural language processor, the concept during an interactive session; and resolving ambiguous input patterns, by the natural language processor, in the natural language input phrase; wherein the natural language processor comprises: a processor circuit; a memory and/or storage circuit; and an input/output device circuit.