Here's a great cover for the Swedish translation of Talmage Powell's memorable novella-length story, "Sudden, Sudden Death" (AHMM, 1957; anthologized many times). The story was published in Sweden in 1971 in a series of mini-sized paperbacks (roughly 9 x 14 cm and 120 pages). The illustration, which I like very much and which is the reason I bought the book, is probably Spanish in origin. The Swedish title means "To Hate till Death".
The mini-paperbacks never really caught on in Finland. There was a series called Mikro-kirjat in the late fifties (they published three science fiction novels, may have to do a post about them later) and later on there was only one series, aimed at female readers.