The web-based application Overton says it is the world's largest searchable index of policy documents, guidelines, think tank publications, and working papers.
Here is more from the site:
[We] collect data from 182 countries and over a thousand sources worldwide with more being added all the time.
We parse each document, finding references, people, and key concepts, and then link them to the relevant news stories, academic research, think tank output, and other policy.
Our products allow you to search these documents and see where your ideas, papers, reports, and staff are being cited and mentioned.
Here is more about Overton, which is based in London. Annual subscription prices for think tanks and other non-university entities runs from $1,800 to $7,200, tiered by publication volume.