> Ask it to provide the link to said document, in literal natural language terms - "provide a link to document D123" -, and it will provide the link in a concise NL sentence as the direct output
I dislike this style of "searching", but it does appear to work. I asked "provide a link to the HTML version of RFC 793" and got back the following URL: https://datatracker.ietf.org/doc/html/rfc793[3. The URL is invalid (for some reason the reference became part of the URL), but it was easily fixable.
That's because you are using a tool that is not made to be a search engine interface: there is no "type keywords here to get links to web pages". The field is "what would you reply to this" - very much not the same.
If you shouted "RFC 1234" or "Declaration of Independence" or "Walt Withman collected page 3" to a guy in the street, he would not reply with a reference to find the documents, directions as if you shouted "Fifth street towards the end" (and even then).
Perplexity is there to give you the references on which it decided to build the reply.
> The URL is invalid
The one I received was perfect. Stochastics.
> the reference became part of the URL
Given the format of the return you pasted, it looks more like the NN encoded a figment merging the URL and a "footnote anchor". It may or may not be so, but we could keep the suspect of that class of possibilities alive.
I dislike this style of "searching", but it does appear to work. I asked "provide a link to the HTML version of RFC 793" and got back the following URL: https://datatracker.ietf.org/doc/html/rfc793[3. The URL is invalid (for some reason the reference became part of the URL), but it was easily fixable.