I had a picture book, squarish proportions, about knights who set off on a journey to confront “the wizard Bone,” depicted in the book as a rather dragon-like creature. The art style is VERY reminiscent of Paul Klee paintings during his Bauhaus period – very geometric, abstract; the ‘wizard/dragon’ is sort of like a Pac-Man with sharp teeth – or something like Klee’s ‘Death and Fire’ – the lettering in the book was by hand, with a very stick-figure style almost like Viking runes; flattened picture-plane perspective, etc.
I do seem to remember seeing the word “Klee” on the cover; but given that he died in 1940, if it wasn’t him, it was certainly inspired by his work. Oval eyes like ‘Senecio,’ panels like his ‘Sinbad the Sailor.’ and generally geometric backgrounds like ‘Castle and Sun’.
It seemed to have been published new in the early 1970s, late 1960s maybe.