For more obscure records, you can usually find the necessary info on Discogs .I have one album that's so obscure (a gospel compilation, so it's not particularly valuable) that there's only one mention on Discogs.--two people say they have a copy; mine would be a third. https://www.discogs.com/release/12515425-Burnice-And-Ann-Rooks-The-Gospel-Singers-Variety-Album

This is a most helpful post in terms of setting out Riff policies. I assume that a writer's photo of an album cover would still have to credit the label. Incidentally, giving credit means that the user isn't guilty of plagiarism, but it's not the same as requesting and receiving permission from the copyright holder to reproduce the image. Still, I doubt any record labels are going to prosecute The Riff or its writers, given the proliferation of album cover images available online.