Paul Klee Paul Klee (1879 – 1940) Swiss. Expressionism, cubism and surrealism influence (orientalism, too). Klee (draftsman)experimented with and eventually mastered colour theory, and wrote extensively about it; his lectures Writings on Form and Design Theory (Paul Klee Notebooks) it was compared with Leonardo da Vinci's A Treatise on Painting.
Painting by Leonardo Da Vinci "Portrait of a beautiful princess" "La Bella Principessa" Very likely Bianca Sforza, on the occasion of her wedding, chalk on vellum, an unusual, not to say unique mix of media. Likely removed from a book.