Just come across this series in "British Library Crime Classics". 5 books in series, all at 0.90 or 0.99 in UK.
From the 'Golden Age'; if you go for
Molly Thynne or
Winifred Peck you'll like these (oh, and a soupçon of
Dorothy Sayers......).
Dunno if price is permanently low, but there it is. First in series here:
https://www.amazon.co.uk/Missing-Mur...ng+or+murdered
https://www.amazon.com/Missing-Murde...ng+or+murdered
https://www.amazon.ca/Missing-Murder...ng+or+murdered
https://www.amazon.com.au/d/ebook/Mi...ng+or+murdered
(A bit more in Aus it looks.....)