This is a set of Moby Books Illustrated Classic Editions mini paperbacks.

The set includes adapted versions of well-known literature: Tom Sawyer, The Prince and the Pauper by Mark Twain; The Three Musketeers by Alexandre Dumas; Tales of Mystery and Terror by Edgar Allan Poe; 20,000 Leagues Under the Sea, Around the World in Eighty Days by Jules Verne; A Tale of Two Cities by Charles Dickens; Heidi by Johanna Spyri.

These books are often marketed as collectible pocket editions from the 1970s and 1980s