This question and answer indicate that when the source of a quote comes from an unverified source, we may say it's "attributed", or that it's "apocryphal". Both of these terms imply that there is some error or uncertainty in who is credited with having said the quote being referenced.
However, I have a situation where the source of a quote is known, but the original version is an idea expressed over a few paragraphs. Over time, with many retellings, the idea has been trimmed down to an efficient and snappy phrase. So, I want to give credit to the person who had the idea, but use the snappy version that people are familiar with.
Note that no one person is known to have come up with the snappier version. Each retelling always attributed whatever version to the original source. Most people assume the original person said the snappy version the first time round.
Using a generic example, I was thinking that I would add the word (paraphrased), something like this:
"A snappy quote is a short quote."
~ Joe McFamousguy (paraphrased)
But I wondered if maybe there was a standard for this kind of thing.
What's the best way to express that this is a variant or version of a quote, but that there is no uncertainty that the source is the correct one?