For any who are interested, a PDF of "Finnish Fireplaces" by Heikki Hyytiainen and Albie Barden (with translation by Aila Rapeli) is available for free download from Albie Barden's (of Maine Wood Heat) blog site:
https://www.albiebarden.com/albie-bardens-blog
This book has been long out of print and has had very limited availability on the used market from the usual suspects.
"Finnish Fireplaces" is a survey of historic and modern (as of the 1980s, that is!) Finnish masonry heaters, most of which feature some form of fireplace, whether open or with operable doors. Some are of the contraflow design, others merely having smoke chambers (and heat accumulators) above the fireboxes. Some designs shown also offer black ovens or cook tops, and a couple of cook stove designs are reminiscent of the Cabin Stove from Firespeaking or Matt Walker's cook stoves.
Even if you are sold on the rockety type of masonry stoves, this is a good reference (though I am still nosing through it, so may be offering a hasty endorsement).
Many thanks to Albie for making this difficult-to-find reference available!