There's many many of these. A lot are due to short length (single drum shots or vocals) or processing that renders the sample almost unrecognizable. But there are a lot of sharp ears out there that are hard to slide a fast one past.
Now, I'm not sure if you are looking to do this for personal gain or as a service to people, but it would be hard to simply write "a piece" on un-cited samples as a one time thing that was not a continuously expanding body of work.
I think it's better for you to provide the legwork if you are wanting people to provide input instead of expecting everyone else to cross reference what is already cited and what is not. If you are truly doing a research piece, then you should expect to provide a body of material that allows others to "fill in the blanks", so to speak, in order to receive feedback.
You stated one example, but a website with an interface and search engine for something like this is actually a dope idea that could expand on what is already provided by that other website.
If the website is not an option, then perhaps you might want to provide a list of specific songs/samples that you are requesting people to provide citation for? I'm not seeing how this would be a cut and dry report...
...unless you are just trying to figure out where the sample for that specific song you asked about is from...in that case, I'd be disappointed in the false pretense, because I kinda took you seriously for a second there. But I know where it was sourced from
