Best tools to summarize and analyze large amounts of text?

Hi,

I have been trying to find cures for chronic illnesses of my parents that doctors haven't been able to treat yet.

I have collected large amounts of text data in the form of ebooks, webpages, text files etc.

Most comprise of medical research, but does not contain much jargon.

I desperately need a tool that can summarize and extract most important info/topics from the collected text.

Example, most recurring themes, 2/3/4 ... word phrases etc.

So far I have tested some online text summarizers, but they have too much limits and are not that accurate.

Several times they leave very important info, such as intellexer.

I have read that agolo is a very good text summarizer, but i have not been able to test it since it does not provide a free trial.

Please suggest the best tool or way to do this.

I will be very very grateful.

Thank you.