It looks as if Mysterious Press/Open Road may have gotten the e-rights to some Perry Mason titles by Erle Stanley Gardner. There are several, mostly from the middle of the series, that seem to have been uploaded in April, 2020, with new covers that have a big red "HBO" bubble in the upper left corner. Early pricing on these seems to have been absurd ($17.09), but now several have dropped to $2.99. That's still too pricey for me for very old backlist, in a series with almost 100 titles, but may be of interest to some folks.
Here's a link for Kindle US that picks up the five that are currently at $2.99, along with a couple of strays:
https://www.amazon.com/s?i=digital-t...1&ref=sr_adv_b
Oh, and the same five are also $2.99, but coupon/VIPable, at Kobo US. Here's a much cleaner link at Kobo:
https://store.kobobooks.com/search?Q...9&fcmedia=Book