I don't have a great background in information organisation / retrieval, but I know of a few ways of dealing with the problem. For structured information, it's possible to go OOish - everything "has-a" or "has-many" something else, and you navigate the graph to find relationships between things. For unstructured information, you have techniques like text search and tagging.

What resources - articles or books - are there that summarise the CS theory behind these techniques or could introduce me to others? I'm developing a system that needs to handle capture and retrieval of information that ranges from necessarily unstructured (advice about X) to structured (list of Xs that relate to Ys) to a combination (Ys that relate to the advice about X) and I'd like to get some insight into how to do it properly.