House of Stratus is a publisher that specializes in older crime fiction, mysteries, and romance titles. They currently have (I think) the entire Perry Mason catalog. I emailed them about the Perry Mason series and got this response:
"Our aim is to have all of our books in pdf, epub and kindle formats by the end of next year. Some John Creasey titles and CP Snow titles are now available on Kindle and Michael Innes and a few others in pdf.
Many thanks for your enquiry.
David Lane
House of Stratus"
Sounds like they are planning to hit
all ereader markets with their books - with
all of their catalog.