Abstract Original Drawing gray and yellow 7.5" x outlets 7" Artwork

My father, Arthur Jacobson (1924 - 2010), was a noted artist and professor (Arizona State University) with a long career and I have his estate of artworks which includes these small oil pastel "sketches" in preparation for larger oil paintings. He handled the medium in a spontaneous and lively way, capturing the clarity and outlets vibrancy of the colors. In his later years, he loved abstract, active shapes and line. This one is an original artwork, untitled (gray and yellow) and is oil and chalk pastel on watercolor paper, made in 1987, 7 " w x 7.5 " h. One of a kind, signed and dated by him.